Pruning Photinia - help!

We planted a 'hedge' of Photinia red robins three years ago and they are looking very bushy now - some more than others - and I am wanting to try to trim them into some sort of order.

When should I do this? Now? To allow the cut branches to recover before winter? Or should I wait until next Spring before they get going again.

I did remove a few low down straggly bits this time last year and nothing bad seemed to happen but this time I want to take out some of the height.

Thanks in advance - great forum

 

Thanks - will get on it, work permitting.

 

I prune mine late June, early July, to reduce it, but also to get back some lovely red leaves, as they tend to go dull over the summer. It's usually fine and looks much better already.