Now is the perfect time to do it. The ideal time to trim them is right before they start their spring growth. This way the wound created by the pruning will heal quickly during the growing season, hopefully before any nasty spores or germs get inside the plant. While the germs that make plants sick are different than those that make us sick, they are spread in much the same way. A doctor would never use the same thermometer on different patients without disinfecting it first.
Most avid gardeners are also weather nuts.
No, I don't just mean whether or not it is snowing. I can tell you if it is cold or not. The plants tell me. No they don't audibly talk to me, although I wish they could. Nonetheless, they communicate to me about their likes, dislikes, needs, what is going on in the soil and the weather.