LADIES: What is an adequate amount of time for a woman to get to know a man before she will seriously date him?

I ask this because I've been told that I'm a fast mover, but also because I have a good friend who is going on 2.5 years talking with a woman he's interested in, who still seems to be very slow to come around. I certainly don't mean to sound insensitive, but it seems to me they should at least be dating by now. Long story short, my friend is NOT someone I wish to see spinning his wheels if she isn't willing to commit to him (wouldn't it be a tragedy for him to lose ten years of his life "chasing the wind", so to speak). Also, he has said that if this doesn't work out in the end, that he will never pursue anyone again. Believe me when I say this is NOT someone who deserves the runaround or to pay for other mens' wrongdoings. Anyway, what are your thoughts on this ladies?