Your ball python will poop when it wants to poop. If it's pooping only when you handle/taking him out of his tank, that's a sign to stop handling. One of my snakes poops, on average, once a month and still eats consistently. A large mouse is probably too small for him as well. Ball pythons can eat live hopper mice straight out of the egg on average and mice aren't that nutritious compared to rats. They're sort of like candy for a ball python. Your ball python is, if I recall, way past being a hatchling and could probably handle eating rat pups or weans at this point.