Below freezing temps are what I use to determine when to winterize, check monthly averages if you are winterizing in a new area. Looking at Syracuse weather it would be pretty early to winterize for us, all the way through October and midway into November average low temps do not breach freezing according to Accuweather. No doubt winterizing in NC will come later than NY.
I would keep close watch on local NC weather starting near the middle of December, with weather being somewhat freakish last few years monthly averages may not reflect earlier than anticipated weather patterns. We empty our tanks within a few weeks of actual winterization anyway, keeps us from getting caught off guard from a freak winter storm.