I don't really like the word "slut.." I will occasionally use it but it's more about how the girl carries herself, etc., not about how many guys she has slept with. I've been with a fair amount of guys, nothing outlandish, haha, but I definitely have self-respect and don't go around fucking people unprotected.
My last relationship, we were friends for months and were together for a little while before we had sex. It felt right, and brought us closer together.
I'm currently in a monogamous relationship that started out as a kind of sex/friendship thing, then we had meaningless sex for awhile during a drug binge, and after the haze cleared we realized we have something that is worth the emotional investment. So, starting off with sex doesn't make someone not worthy of being in a relationship. Maybe it just means they like sex.