If you want to get a piercing, do it for you and you alone. If YOU think it's cool, then guys you're compatible with will likely think it's cool too. Besides, a nose stud is so minor and mainstream. It says more "I'm a little quirky" than "I'm a scary freak".
It's really only worth dating guys you don't need to change yourself for anyway. If they're so shallow or uptight that they wouldn't consider talking to a girl with a tiny piercing. Ehh. What's the point really.