Much, much, much too young to sex. Polish can be almost as difficult to sex as silkies.
Agreed, much too young. I know you said you read online that females have a rounder poof while males do not. Can I have the link to the site you saw? I'm pretty sure it is the same one that I saw, and I will tell you for a FACT that it is not right. I have a female golden laced polish hen, and her head "poof" was not round at all, instead, it matched what they said the "males" were like. Unfortunately, you're just going to have to wait (a hard game, I know! I hated waiting to know if mine was female or not!)