I'm afraid you have to be 24 when you walk through the front doors of IOT. End of story. I tried to get an age waiver for 7 weeks, they would not budge, and offered Nav, not Pilot.
As it was they found room on an earlier course and I started IOT as pilot. Unfortunatly I screwed up IOT and was kicked out. At the time I wouldn't take Nav, now I'd give anything to get Nav. Doing ATPL exams instead. Boring as f**k, and I hate being a civvy.
F