I think that first shot is the one to train for when it comes to hunting.
I like to "warm up" by drawing my bow and arrow and anchoring, this is what I do every so often when I am hunting, practice that perfect anchor. When I warm up that way before I shoot at home or the range, my first shot is usually good to very good. My bane is the 3-d shoots. Warm up and the first few arrows are good then out to the course and some good some bad but it does add to the physical build up and usually is fun and, I think it also prepares you for those high pressure intense shots (nothing like having a few bystanders/ hecklers/ "friends" to add to that). All in all it is shooting the bow and I just can't stay away from that too long. As it gets close to the hunt season though I focus on the many anchors, few shots routein, that has worked best for me.