I measure mine using the AMO method, 1.75" in front of the deepest part of the grip. That way they're all measured, tillered, and weighed the same, regardless of grip shape or depth. If I make a bow for someone else, when they tell me their draw length, I ask them how they measured it, then do likewise to tiller and check weight.
You don't have to use the AMO thing, especially if they're just for your own use, but you should measure and tiller your bows on the tillering tree or stick, the same way you measure your draw length when drawing it by hand.
By the way, I always design and tiller bows at least an inch farther than what they're intended to be shot at for a bit of a safety cushion.