The opening Champions League game against Benfica on Wednesday is an occasion which the Celtic manager and his players have been looking forward to for the past couple of years.
But because Neil had to wait until he knew if his team had qualified for the group stage before he could make moves to strengthen the side, then saw some his players head off on international duty, he has not had the chance to work with the squad anything like as much as he'd have wanted.
Now, let's get one thing straight. Efe Ambrose, Miku and Lassad Nouioui have not been brought to Glasgow to play in the SPL.
They have been recruited to give Celtic a better chance of being competitive in the Champions League.
And it is vital Celtic get off to a good start when Benfica come calling this midweek.
But Neil has a real dilemma. With only tomorrow's game against St Johnstone at McDiarmid Park in which to blood them into the team – and there is no guarantee Efe will be back in time with all of the necessary paperwork to allow him to take part – it would be a gamble to consider starting them against Benfica. That's more of an issue with Efe than it is for Miku or Lassad because a central defender really needs to have the chance to know who is playing beside him – and behind him – as any misunderstandings when you are in such a key position can have serious consequences.
The last thing Neil will want is to pitch any or all of them in, only for them to get off to a bad start in their Celtic careers.
But at the same time, he will want to be able to call on them for a game which is so important.
It's going to leave him with some big decisions. But then that's what being manager of a club like Celtic is all about.
Neil is very confident in the players he already had before the late signing rush as the window was about to close. After all, they were good enough get through the qualification rounds to secure a place in the group stage.
That was a real test of their character and quality. But playing against the likes of Benfica, Spartak Moscow, and, of course, Barcelona, is an even stiffer test.
The bulk of them are, as yet, untried in the Champions League, and it is only when you get there that you find out if you have what it takes to handle all that comes with it.
You can be sure Neil has had a team in mind for this game since Celtic qualified.
But it's not an ideal world, and often, your best laid plans can be rendered worthless because of injury, which is why you want options open to you.
The new signings offer greater choice, but perhaps not so soon because this international break has really compromised their integration to the squad.
There are another five group games after Wednesday, so there is no need to throw them in.
Neil can only assess them in whatever training sessions they can arrange, and perhaps give them a little game time at Perth, though, after being held by Hibernian, he will want to win against St Johnstone to ensure there is no hangover going into the Benfica match.
It will have been a frustrating time for Neil as he waited for all of his players to return from international duty.
He already knew he would have to go into Wednesday's game without Georgios Samaras, who injured an elbow playing for Greece last week.
That will be a massive blow because Sami thrives on the big stage, and he played a huge part in getting Celtic through to the group stage.
Scott Brown is another on the injured list, but I fully expect him to be leading out the team.
He's the type who will play through the pain, but Celtic need to be careful with him and not allow his willingness to exacerbate his condition.
Scott's drive and enthusiasm is a real asset to the team, but the approach and attitude of everyone selected has to be positive on a night when so much is on the line for everyone at the club.