When we go to South Carolina or Florida the week of Christmas, we leave Indiana winterized and once out of the "freeze zone" unwinterize "there". We have found over the years, that it is pretty safe to unwinterize once we reach midway through Kentucky. If campgrounds have water turned on at the campsites, then it's pretty safe to go ahead and unwinterize.
Coming back home, usually on Dec 31, we winterize at our destination spot, right before leaving. We use to plan on driving one day, spending the night in Tennessee and winterizing there, then driving the rest of the way home. Except Christmas week 2017. I winterized in South Carolina and we ended up driving straight home as temps were called to reach as much as 10 below zero in Indiana that week.
We have in the past, until we learned about where that line is where campgrounds leave water on, stayed winterized until we reach Florida and stayed the first night traveling in a motel. Those days are gone now, since we've learned about where that line is, between the freeze zone and the non-freeze zone is, and now plan on campgrounds and unwinterize the first night.