Most Helpful Guy
I don't think you need to on a first date, seems a bit premature to be talking about sex and stuff already. But before the relationship gets serious, yes.
Most Helpful Girl
Not the first date; the first date should be just about enjoying each other's company on a casual level. It's after further dates, that you start to discuss what type of relationship you are looking for and how serious.. and what you will/won't put up with.
If a guy is with you for the right reasons, he won't mind if you're a virgin. If he's with you for the wrong reasons and he does mind... then good riddance. Don't worry about upsetting the types of guys that don't value you.