How long should you date a guy before you have sex with him? A month? Two? Three?

This topic was brought up at work. How long should a woman date a man before she has sex with him? If she does it within the first week is she a slut? If she makes him wait a month or two, will he respect her more? Does figuring out when the best time to have sex really matter or should we not put limitations on physical expression and just do what feels natural regardless of when you feel it? (Observing all precautions of course).