Sorry but I personally wouldn't and certainly not now - the buds will already be forming for flowering early next year. They are a shrub, like camelias and azaleas I never go near with a pair of secateurs - except to remove a damages branch or the like. I would assume that they can be pruned immediatly after flowering but don't count on it could be risky, as I have never tried it.
I agree with Fran, Only prune if you really have to, and then I would remove entire branches in winter if they are not wanted. Dont do any trimming up.
