My husband is currently at Keesler AFB for Air Traffic Control?

It says the school is 72 days on about.com. They told him his last day would be September 19. But now he keeps telling me there is AFI possibility where he'll have to wait a week or more to start blocks 3,4,and 5. He's been there since June 1. Does AFI always happen? Or is there a good chance that his last day will be in September? I would think that since they give them a date of completion, that they would stick by it. I'm confused about all of this. He's Phase 2 all ready and in block 2. So how long can I expect him to be gone if he does get AFI? Has this happened to anyone that has went through ATC at Keesler? Thanks in advance!