Gordy Krahn of North American Hunter offers a new perspective on bow practice. The way he sees it, there are no warmups when you're in the field.The situation puts you on the spot whether you're ready or not. You may have been sitting for hours, but it's instantly GO time and you need to be able to pull off that shot.
Gordy approaches practice in the same light. You should focus on that first arrow, as often that is all you'll get for chances from your stand. Keeping that frame of mind might just develop muscle memory for the moment of truth.