To be honest a lot of people just criticise other people's looks for something to talk about/ slag off ugly people to feel better about themselves. I know I do it sometimes but it doesn't mean I'm looks obssesed or would be unable to understand another persons situation. He's prob the same
Your situation is a very tough one and you could prob do one of 3 things.
1. Tell him and take the chance that he might reject you as the early stages of most relationships are lust fuelled. You could either make a big deal of it or show him your at ease with it in yourself. One of my friends has alopecia and wears a wig. She's never short of men, but she tells them earlyish on in the relationship but never makes a big deal of it, although I know she hates it and gets upset about it sometimes.
2. Wait until the two of you get closer and then tell him once you think his feelings are stronger than lust. Prob with this he might percieve not telling as a lie and this may break you up.
3. Not bother with him and prevent yourself from the possibility of getting hurt.