How soon after long term relationship break up...?

My crush just broke up with his girlfriend of nearly 3 years (to my surprise) a week ago. I haven't had a bf but to me, a 3 three yr thing would be a big deal so idk how long he would want to leave it before moving on. however, we have been good friends for a few months now and imho flirty even when he had a gf (although it could be seen as just friendly). so in the last few days the flirting seems to have gone up considerably to the point where we may as well just date. Untill recently, I would probably have frowned on such a situation but I don't see the point in acting any differently than natural just to delay things. So my question is; what do you think if we were to get together soon? otherwise, how long should i leave it?