The leading points scorer in Lions history is adamant that tour places are still very much up for grabs, with selection dilemmas getting even more difficult as the deadline approaches.
"The next two weeks are absolutely crucial. It's an old cliché, but there's still an awful lot to play for," said Irvine.
"The next couple of rounds of the Championship will probably go a long way in determining who might and might not go on tour.
"Selection is going to be extremely difficult because there are so may positions wide open where there are a number of genuine contenders. It's going to be a very long debate as to who does and doesn't make the trip.
"After some games it looks as though selection has cleared up a bit and then after the next game it all changes again. Things are very wide open - I don't think there are all that many certainties pencilled in. There are a number who are highly likely to go, but certainties would perhaps be a bit too strong.
"There's still two games to go in the Championship and there's a good few league and European matches left as well so it's still quite early in the selection process."
Gatland has spoken publicly about his desire to select the right mix of youth and experience for the 125th anniversary adventure and Irvine feels the Championship has certainly given the selectors plenty of food for thought in that department.
A number of old hands have reaffirmed their tour credentials, while a new crop of youngsters have already shown that they can cut it at the top of the international tree.
Starring for Britain and Ireland's elite in the southern hemisphere is clearly another step up but Irvine knows better than most that Gatland will select on form and fitness rather than on reputation alone as the Lions look to avenge their 2001 series defeat to the Wallabies.
"What's pleased us is that one or two of the older, more experienced players have started to come good and put their hands up, while the most exciting part is that one or two youngsters have emerged who perhaps a year or two ago were either unheard of or hadn't really made a name for themselves," added Irvine, who says selection discussions are ongoing between Gatland and his coaching staff.
"We're going to have a combination of an old guard that have been there and got the badge of honour so to speak and some really exciting youngsters.
"It's Warren's call because ultimately he's responsible for selection but, if you look at his track record, he has been quite innovative and adventurous in bringing through young talent, both when he was with Ireland and, more particularly, with Wales. I wouldn't be surprised if some youngsters with real potential find themselves on the tour. I would say that there's a pretty decent chance of that happening.
"There was a selection meeting a couple of weeks ago and there's another one going to be taking place at the end of the Championship, with a final selection call towards the end of April. But Warren and his assistant coaches talk all the time and, when they're having their discussions, it's effectively an informal selection meeting."