Congratulations! I'm guessing he was still walking, when you shot? If he was, see if you can find a way to practice that shot. A taut rope stretched between a couple of tree, a bag target, and a pulley system will make it easy to gauge how much you need to lead them by.
By the way, there is no need to apologize for the length of your story. We've got some seriously long-winded folks around here, myself included, and a story the length of yours would be considered the introductory sentence to their tales.