First things first - dead-head them unless you want hips for flower-arranging or something like that. Personally I wouldn't cut back hard just yet. Leave as long as you can, but do it before the Winter winds can cause rocking and root disturbance. Also, it gives more time for the sap to 'drain' (best word I know) and goodness to be resorbed. I am by no means a professional, but my roses always do OK. I do know someone who has cut hers back hard last week. You pays your money …...