Have A Friend, Now Wants To Be Boyfriend?

In my experience and from observing so many friends that have done the same thing, it all depends on the level of honesty and trust in your friendship. Is he someone you can become serious with? Is he "just seeing where things might go?" Find out directly what his intentions are. Ask him outright! If he's not sure, tell him to hold off until he's sure what he wants. If he knows what he wants, then ask yourself those same questions: "Do I know what I want and what are my intentions?" If you are both on the same page, then I say go for it. But if it's just a tentative curiosity of closeness because you are already friends or if he's only attracted to you, then it's not a good idea and should immediately close the door on it.