Hi teainthegarden, I understand fully how daunting it can be when our climate is unstable, very different from season to season due to warm when we are expecting cold, wet when we want dry and hot when it's supposed to be going into winter mode, you are NOT alone.
Most gardeners are experiencing the exact same NEW conditions as you are and with experience, it becomes easier to gauge when to carry out the normal tasks to suit the weather rather than the seasons HOWEVER, as you are trying to prepare the plants you have when the weather is not quite right is tough to get right, but NOT impossible IF you are prepared to take a bit more time and prep properly.
My personal opinion would be to leave any FULL pruning till Early spring once you see new tender shoots arrive, these are leaf shoots rather than flowering buds. this new tender growth is a sign nature is feeling the soil begin to warm up and it's time to start growing again.
All plants want to grow, set flowers and make seeds, after flowering has past, we gardeners are the ones who tamper with nature and alter the plants growing conditions, flowering, by taking away spent flowers so the plant will make more flowers over the whole summer for us to enjoy, by removing the seed-heads being formed, we trick the plant into making more flowers for seeds, nature wants the plant to scatter the seeds so nature can keep the species going. we want to save the plant energy by removing the seed-heads, also we need to cut out the long or used up branches from the shrubs we grow, this rejuvenates the whole shrub and gives it time to send out new shoots, that's exactly what you want to do NOW instead of waiting till the plant AND right weather conditions to give the best chance of recovery.
A long winded explanation about nature and human interfering with each other but hope it helps you understand.
IF you have to prune the shrubs right now I would be careful of how much pruning you do, maybe HALF the length of each branch you want to prune, this will remove the weight and prevent heavy snow breaking the branches in the wrong areas, this half shortening of the shrub will allow the plant to stay alive yet get through the winter better.
Any new shoots made in the warmer weather your having now, will probably be killed off by the type of cold you have in your zone, BUT in spring, there will still be enough length on the branches to allow you cut out any damaged / frosted or dead stems, spring is the best time for pruning smaller plants as the sap has not yet began to rise and they recover better.
IF you prune NOW, I would add a thick layer of mulch to offer protection from the freeze / cold/ or snow you get, this will help give insulation to some of the shoots while trying to get through a harsh winter and newly pruned.
Considering I don't live in you climate at winter, I can only assume that your plants have survived up till now because they have outgrown there normal size and shape so maybe I'm being over careful but you will know best re how cold you get BUT, better erring on the right side.
Good luck, hope all works out for you and you have a great show from your plants next year.
Best Regards.
WeeNel.
