Well for me not much! Felt like a friggin waste of time. Oh! BTW, I'm normal. Great! That took about 2 minutes. I spent more time driving there and trying to find the office then I spent in the office. About 5 years later my sister went to the same place. I told her what he was going to say to her. She told me it was exactly like I told her.
I wouldn't worry they'll probably just ask you a bunch of questions. Not sure. My appointment was easy and quick, really no big deal, well for me anyway.
Hang in There.