I would wait unless your workload dictates you start now. I am in zone 5 just a bit west of you. I never start until late Feb. early March. We are bound to get some very cold temps yet before spring.

This post was edited by TurCre on Tue, Jan 13, 15 at 23:14

I prune mature apple trees now and leave all others until later as a general rule. When I've broken that rule in my zone there has yet to be a price to pay. If there is a chance it will fall below -20 F. where you are after you prune, results might be different. Probably best to wait with young and tender trees.