Dress smart EVERY time you go into the AFCO, not just for the interviews etc.
I remember sitting in my AFCO waiting to speak to someone, and the number of 15-yr olds who walked in wearing tracksuit bottoms, jumpers and baseball caps was incredible. If you'd heard some of the things said after they'd left the office, you would wear a suit even to just walk past the window!
Everyone at my P2 presentation was in a suit. 2 of us out of the 11 in that room are off to basic training very soon.