I'm not an instinctive shooter and probably never will because my beat up old shoulders won't let me practice enough.
There is a lot of good information on this tread but I think that I have one thing to add.
Watching videos of good instinctive shooters like Terry & others, I notice that not only do they begin aiming before drawing, but they also begin setting up their stance & alignment before the shot and finish aligning during the draw.
One of the things critical to good accuracy is to draw the bow the same distance every time. It's certainly not the only thing, but it is one of the biggies. This is partly achieved through shoulder and body alignment.
I don't know how Terry learned to do this, but he obviously did.
Idealy, aiming, alignment and balance is achieved before and during the draw. Then when you hit anchor and are on target, there is no reason to continue holding.
However, if you need a little longer to be sure that you are aligned and on target, then by all means do so. It is a little less efficient, but every archer needs to learn what works best for himself. Archery is not about efficiency, it's about accuracy.
I hope that this is a constructive contribution to the conversation.
Allen