Two schools of thought from another East Coaster. The time to prune your roses is NOW to remove any winter damaged (blackened or browned canes/stems) and to prune out any dead wood or old thick wood from the centers of roses. Any long stems that were whipping around in the winter should have been cut back in the late fall to prevent this whipping around in the winds. Hybrid teas can be cut back now and so can any of the 'Knock Outs' to about 18-12".
These two varieties can take a hard pruning and will bounce back again.
But if you like your 'Knock Outs' to be at 4' high you can leave them be but just remember these roses bloom at their tips so all the blooms will be at the tops and sides.
Because of our changing weather, you may see more winter damage a few weeks after you have initially pruned, its normal and its okay to trim back to green stems. Do not be shy about pruning-- roses are tough!!
☼The best place to seek God is in a garden. You can dig for him there. GBShaw☼