Pruning in March in your location is fine. You will have missed most chances of a deep freeze and possible "winter damage" from pruning. many large operations prune up to the time they spray the first dormant oil spray. you didn't mention what size trees and if they have been pruned and cared for up to this point in time. I would recommend doing what you can this year to take care of any obvious problems (dead wood, limb rubs and any big cuts that are needed to open the the canopy for air circulation and to reduce shading of other branches) and not worry about some of the finer pruning this year. Many trees on dwarf rootstocks unless overly vigorous can go a year or two with little or no pruning.