Our first camping trip often occurred before temperatures were above freezing. With previous RVs we would travel south until we reached appropriate temperature then in the campground we'd flush out antifreeze. With current trailer I pick a relatively warm day maybe a month or so of departure date and flush out system and leave the trailer plugged into 120 volt power with heated tanks keeping things thawed and ready for use. Also leave a small electric heater on in the cabin to prevent freeze ups in internal plumbing. It's really a little different for each RV depending on how it's equipped and what your storage situation is.
Good luck / Skip