A 2 moa dot at 200 yards is theoretically around 4" in diameter, but, in practice, it appears larger than that. I need some edges to show around the dot on the aim point, so I tend to use a black circle around 8" in diameter and then box that in with a light colored square to isolate the dot from the background. That makes it easier to see the red dot and to see whether the dot is actually in the center of the black circle. But, even your pulse will move the dot so some sense of timing is needed, but one has to be careful not to force the shot. So I accept a little wobble and try to release the shot without moving the gun, even when the dot isn't perfectly centered. I will throw the shot off a foot or two if I force it or time it. That's a lot more error than letting the dot wobble a little but executing a perfect trigger release.
Joe