if youprune them after the first blooms have died you will have a second blush later on .prune them by cutting back to a bud so that any new branches will go in the direction you want them to and then once you have the right shape you just keep it under control.its not as hard as it sounds and there is a lot of nonsence written about pruning i have heard of some people pruning with chain saws!! ps if you prune before the winter as well it tidies everything up gets rid of all the dead wood and stops it from blowing round too much