Lots of great advice in this thread. Like
@LME I find it hard to hold a rifle still with sights on target. So I like his method of incorporating movement into aquiring the sight picture and squeeze as soon as your sight picture matches what you're picturing in your mind. Coming up on the target from directly below and squeezing at six o'clock works best for me because windage is already aligned and being held steady and the rifle recoils up. If I have to hold over the intended POI (as is the usual case with iron sights on milsurps) I might try coming in horizontally from the side while holding the elevation steady. I don't know how this method translates into moving targets because none of the outdoor ranges I can shoot black powder at feature or allow moving targets. I need to figure out some way to get in this training.