I think the only risks you have to worry about with sex too soon are these:
1) If he'll think less of you because of it. I haven't really encountered this but it could happen.

2) If he'll pursue less once he's "won" you - Mr Big Lots was like this, all over me up to the third date, never got that kind of effort from him again (he was a major league Love Avoidant though).

3) The BIG risk - you'll get attached to someone before you know what their red flags are. This is really dependent upon you. I have a friend who definitely CANNOT do casual sex - she gets too attached too easily and has trouble getting unattached because she's a little obsessive. For her, it's really important that she wait until she's sure about a person. I, on the other hand, being a product of the late 60's early 70's, don't have a problem with casual sex if it's someone I'm really attracted to and comfortable with. At my age I can easily accept that some men will just be flings, some will be long term friends with benefits but not boyfriend material, some will be boyfriends (and some will look like great boyfriends and turn out to be all messed up, like Mr. Tall Dark and Handsome.) If you want to and you feel safe and you use condoms (no glove no love as my friend says) and you are sure you can keep some objectivity, go for it.