I think if the soil's workable, and you're not dealing with a very young / seedling age plant, you'll be fine. How cold is it already?

Our winters in Oregon are basically cold, but not harsh, until you get to the tail end of December. That gives a lot of plants, especially hardy perennials, time to keep growing roots while the top stays dormant. If your winter is similar, and you don't expect harsh weather for awhile, go for it.