I started thinking about it, and I'm not sure if I do one more than the other during a match. I think it has to do with how fast I'm trying to get the shot off, based on distance to the target.
I do not cock anywhere close to the beginning of the draw. The gun is definitely pointed downrange, rather than at the floor. But I wouldn't wait until I've acquired the sights, either. Why disturb your sight picture by cocking then?
In essense, it shouldn't matter when exactly you do it as long as it's well after clearing leather and before aiming.
Obviously, the trigger finger habit is the most important part.