Best time to prune is in early Spring in conjunction with a good dose of fertilizer. At this point the plant is getting charged up for the new growing season and can throw all of that energy into new, healthy growth. That being said, I cut non-tuberous begonias in our greenhouses back at any time of year. They always survive if you're careful. My advice would be to pinch the tips now to induce growth farther down the stem and then remove what you deem necessary in Spring. I have cut some angel wing varieties back to 6 inch leafless stems (in Spring) and they leafed out again fairly quickly.

What I do sometimes, knowing it's best to wait for spring, is cut maybe one stem to the ground and cut most the bare stem off the top and root it. Then when more start to come at the base, I might take off one more stem. Taking one stem at a time will give it time and strength to come back better. But you need to be sure you can give it plenty of light, otherwise it would be best to wait for spring. Most canes prefer more light than they usually get in the house in the winter. And the cuttings root better in the spring and in more light, unless you have a light stand.