We typically leave upstate NY in early January with our coach loaded just as it is any other time. The fresh tank is full when we leave and the waste tanks are empty. We do keep a small 700 watt electric heater with a thermostat in the wet bay for use during over night stops when the temps are forecast down into the mid 20's or lower. We travel down I88 to I81, stopping for the first night at the year round Jonestown, PA KOA.
Since we're usually still living in our coach when it's time head south after spending the holidays with our kids, de-winterizing isn't an issue for us, but in past years when we did winterize, we turned on the motorhome heat st at about 50 degF a couple of days before we left, turned on the fridge, and started loading clothes, non-perishable food, etc. The day before leaving, we loaded up the fridge and freezer with pre-cooled, pre-frozen items and filled the fresh water tank. On departure day, we turned up the heat to 70 degF, loaded any last minute items, unhooked the shorepower, made sure the house was prepped and locked, and headed out. These days, it's much easier and no different than leaving the cottage at any other time of the year. Lock the doors, hook up the toad, and roll out.