When can I prune Photinia davidiana to keep it tidy also to preserve the colour

All information seems to lead to this plant being a tough brute, and can get really out of control if not kept in check, so i would wait until after flowering and whack it about.

We prune ours four times a year. We have shrubs that are 17 years old and they are still only 2 foot high. By pruning them regularly - when losing their red colour and going and uninteresting brown - we get lots of fresh red growth. We try and disguise the cuts and keep the plant a pleasing shape.