The Shaymen have announced two additions so far this summer in midfielder Jack Hunter and winger Sam Smart.
But Millington says two more new faces have been all-but sealed, and should be signed off later this week.
Millington told the Courier last week that the club had made offers to eight potential new signings, and says that two of those are now much further down the line and agreed in all but signature.
"We still have some those that we're trying to progress to the latter stages, and there's a couple of those where the targets are actually investigating what else is there for them at the moment to make sure that when they make their decision, they make the right decision for themselves," Millington said.
"So we've got to respect that, but in saying that, we'll also make sure that we protect the interests of Halifax Town.
"We won't just wait for people to make their decisions, we will continue to endeavour to find other people to fill those positions.
"I'd hope that we're a couple further down the line by the end of this week.
"I've made no secret of the fact I'd like to be up to a squad size of 18 players by the beginning of pre-season, which starts in two weeks, so that's plenty of time for us to get up to that level.
"As we know, at this time of year it's important to just hold your nerve a little bit as well, because there's an awful lot of players I'm speaking to who are trialling through pre-season at Football League clubs that we'd be interested in.
"They're not all going to get offered deals at those clubs so as we get into pre-season we know that more and more players will become available who we currently can't attract because they're trialling at a higher level or they're chasing a slightly higher wage than we can afford.
"But if we've got some positions left to fill, I think we could make some really astute signings at that stage as well."
When asked if he felt confident of having a squad of 18 by the start of pre-season on July 4, the Town boss said: "That's my hope, yeah, and I think it's a realistic hope.
"We're at 15 at the moment and we've got a couple very close, so I expect that to happen."
Millington insists there is no lack of action or ambition behind-the-scenes at the club.
"It's a hard time of the year for everybody really, the management team are working really hard trying to identify and speak to the right targets," he said.
"The media team are busy trying to put together information on potential signings and signings that we bring in because they're so keen to keep the fans fully informed or as best as they can without putting negotiations at risk.
"And players are trying to make decisions, we've got to remember these guys are young men and have an awful lot of different pressures on them.
"Some of it's based around the football opportunities, some of it's around the level they believe they should be playing at and some of it's based around the financial benefits of making any particular move.
"We forget these are often guys in their early 20s making quite big decisions so they need as much help as they can get to make those right decisions.
"So there's an awful lot going on but what I would say to the fans is they mustn't think that there's a lack of action and a lack of ambition at Halifax.
"Everybody's working all the hours they can to make sure that the right people come to the club to help us fight for promotion, and that's ultimately what we're going to try and achieve this season."
The Town boss is confident The Shaymen are able to compete in the market for new players too.
"I've said it before, and I truly believe that there are different ways to measure value," he said.
"My job is to try and get across to our potential targets that it's not just about pounds and pence.
"Players that come to us, the likes of Tyrell Warren, Tom Bradbury, Billy Waters, they get an opportunity to play regular football, a style of football that's attractive to watch and enjoyable, and an opportunity to develop because the backroom staff are so well qualified and well intentioned in trying to help these lads get better, so there can be a measure of value in that, which in time does turn into pounds and pence, but in the short term it might just be recognising where the value is.
"So we compete on a number of levels. It isn't always the pounds and pence that we can compete with, but I believe in other areas we offer more value than most teams and we'll continue to bang that drum and try and offer players an environment to come and develop, come and compete at the right end of the division and progress their careers with Halifax Town and then at some point, beyond at Halifax Town.
"We will make sure that if we identify players who can help us out significantly then we'll look to find innovative ways to try and make that pay financially as well for them.
"So we wouldn't rule out going into battle with clubs who've got much bigger spending power than us either."
Strikers and centre-backs remain the priority for the Town boss.
"They're the key areas for sure," he said.
"We certainly won't be turning down any good wingers and full-backs either.
"I think we're fairly solid in the centre of the pitch and we have some really excellent options there, and if we can move Luke Summerfield across the line that would be the final piece of the jigsaw in that area of the pitch.
"Of course the focus has got to be getting the right strikers in the building and having centre-halves who can come in and hit the ground running because we've got to maintain our excellent defensive record from last season, and to do that we need to make sure that we get the right centre-halves in."
On what he would like from his attacking options, Millington said: "We want players who offer certain differences in their style of play, but we've also got to have some similarities because they've got to be able to press, they've got to be able to deal with the size of The Shay, they've got to be able to link play by receiving it, whether that's up against a defender or in pockets of space to then help us get up the pitch, they've got to have some ability to run off the shoulder and threaten in-behind if not get on the ball a great deal in-behind.
"Those attributes have got to be there in some measure, but of course, some players will be stronger in the air and receiving longer passes, and some will want it nice and short and in more shorter combinations, and we'll look at trying to get a combination of strikers that have got the ability to do all of those things."
On the future of midfielder Summerfield, Millington said: "We're very close (to agreeing a new deal), yeah.
"We've had some really good discussions with Luke's agent while Luke's been away on holiday.
"He's due back at the end of this week and we expect that to hopefully be wrapped up fairly quickly once he arrives back."
Defender Tyrell Warren left The Shaymen over the weekend to link up with ex-Halifax boss Pete Wild at Barrow.
"Very sad to see Ty go," said Millington. "From a personal perspective he's a lad I know well and enjoyed working with him last season.
"He's a good player with an awful lot of potential, and I think he would've benefited from another full season with us, playing regular football.
"But he had an offer that he felt was too good to turn down and after a lot of soul-searching, decided he couldn't refuse it.
"It was always a tough decision for him. If you put it down purely to the benefits football-wise I think Halifax Town would have been the obvious option, but then when you talk about adding in other factors like potentially playing at a higher level and earning a decent amount more, then it starts to tip the balance a bit.
"And there's other people who'll be encouraging him to go and test himself at the higher level. My view is that he would have been able to do that in time anyway and could have just benefited from another season with us.
"But we send him with our best wishes and we hope he kicks on and fulfils his potential."
Millington says work is already well underway on finding a replacement for Warren at right-back.
"We've got some interesting conversations to have because obviously Jay Benn showed what he's capable of last season and deserves his chance," Millington said.
"We need to look at what the next right-back is going to have to do to complement and offer maybe some of the things that Jay doesn't quite offer.
"So we'll look at that, we'll measure it against him, and we'll start to identify the names of who we want to go after.
"We've already enquired about a number of players with agents and also with other clubs, to try and identify whether we can bring them in, and that process had started before Ty had made his final decision, so we're well prepared and we're well on with that."
It was one out, one in recently though with the arrival of Sam Smart from Eastleigh.
"He's a perfect fit for us," Millington said of the wide man.
"He's really exciting. He's coming in as a right-winger to work alongside Jamie Allen.
"He offers a lot of similarities to Jamie in that he's very direct, very, very quick, exciting when he's got the ball at his feet.
"He can operate inside in one of those advanced midfield or number ten roles as well, he's got a threat from there, and he can also come in off the left, so he's versatile.
"But the most important thing is he's exciting, so when he's got the ball at his feet he will terrify defences, and he'll have the ball at his feet with space in-front of him at The Shay and awful lot, which will play into his strengths.
"So he's a very exciting addition, and I think once the fans have seen him a couple of times they'll really understand what he's going to offer."
Smart has signed a one year deal with an option of a year's extension.
"We'll look in time at potentially adding another left-footer to play down the left," said Millington of his options in the wide areas.
"We've got some targets but they are not a matter of urgency at the moment, and we'll work on them a little bit slower than some of the other positions we want to bring in.
"I won't rule out bringing in another left-sider."
Backup keeper Tom Scott signed a new deal last week, and Millington is delighted to keep him at the club.
"Tom is a phenomenal young keeper and it's hard for the fans to appreciate exactly what he does for the team because they don't see him turning out on a Saturday afternoon," he said.
"But what we need for the benefit of the outfield players are two good keepers who give them enough of a test in training to make it a worthwhile exercise within training, and Tom does that.
"Tom plays at such a high level in training that he really does push Sam (Johnson). It's important for Sam to have some competition, which Tom does provide, and also it's important occasionally, in training, Tom takes some of the burden off Sam because obviously we don't want to fatigue Sam too greatly and put him at any serious risk of injury because he is so important to us.
"So he's one of the unsung heroes of the group really.
"We do utilise the youth team keepers an awful lot, they train up with the first-team on a regular basis, but just for that continuity and that quality within training, it's vital to have a strong second choice keeper and Tom provides that."
Scott could be rejoined at Halifax by defender Pierce Bird, who was on loan at Town from King's Lynn at the back end of last season.
"Pierce did a really good job coming in to us from King's Lynn," Millington said.
"He's still a King's Lynn player but somebody who we would like within the group if it was possible to bring him in.
"He is a player that will attract other clubs' interest and I'm sure that King's Lynn are dealing with enquiries around Pierce, but if we could come to an arrangement that worked for our football club that got Pierce Bird in, we would do that, but it's quite a complicated situation."
On whether former Grimsby winger Erico Sousa could be one of his targets, Millington said: "He's a player who we met up with last pre-season and spoke to before his move to Grimsby.
"He would fit into what we're trying to do in terms of style of play and he's a good, honest character just coming into the prime of his career.
"He's certainly someone we wouldn't rule out talking to at some stage."
And on former Boston striker Danny Elliott, who scored 31 goals for The Pilgrims last season, Millington said: "He's a player who we admire a great deal. He's certainly young in full-time football years and has got an awful lot of potential to grow into.
"He's a player that we're aware of and we would be really interested in attracting to the football club.
"We know that he's got a lot of interest from other clubs and we're not shy about competing with those clubs when it comes to trying to meet the best interest of Halifax Town."
Millington says Town did miss out on one target though.
"There's only one who we got a long way down the line with, who actually had some difficulty deciding between ourselves and a League Two club," he said.
"In the end they did go for the League Two option but I think it's a real credit to the staff and for what we're doing at Halifax that we were in the conversation right down to the wire, and the fact the club he chose was at a higher level and was offering a significant amount more money still didn't have them completely in the bag right until the end."
Millington says a new captain should be decided on by the beginning of pre-season.
"We'll be more than ready by then to start putting a leadership group in place and that'll involve establishing who the new captain is going to be," he said.
"That will be done between the staff as we approach pre-season."
Millington says there will be triallists at the club during pre-season.
"As players become available who are currently trialling at clubs at a higher level or are in with a club where they believe they're going to achieve a better financial package, as and when they become available there are some we'll invite in immediately to spend a bit of time with us, so they can see what we can provide for them and vice versa, we can get to know them a little bit more intimately before we make any firm offers to them," he said.
"There won't be high numbers of triallists but there will be some players who we bring in to experience the club so we can get an experience of them before we make a firm offer."
Former Leeds United youth coach Andy Cooper was announced as Millington's assistant manager yesterday (Monday).
Millington and Cooper met on a coaching course, and Millington describes his new number two as bright and intelligent, and says he will fit into the backroom team's way of working.
"He was the first person we began speaking to," Millington said. "It's been done in a really thorough manner on both sides.
"He's been really thorough in his questioning and getting an understanding of what is expected of him and what his contribution is expected to be, and I'm really pleased it's all been agreed."
Millington says the club's pre-season friendly schedule is confirmed and the club is in the process of liaising with the other clubs involved to arrange when they'll be announced.