De-winterizing works best if you have access to city water and a sewer dump point.
I would stay winterized until I got far enough south that your overnight temps are right at or above freezing. I carry a few gallon jugs of water in the RV until I get to where I can de-winterize so I can use the toilet, brush teeth, etc.
Did the person that winterized use RV antifreeze "red stuff" ? If so you have to flush it out with plenty of water.
Your operator's manual has instructions on how to winterize, you just reverse to de-winterize.
To summarize, you have to make sure all the water valves are closed, the hot water heater bypass valve is set to normal, all the water drains are closed. Once you connect to water you'll open valves and burp all the air out of the system and flush out any red stuff.
Make sure you don't operate the hot water heater until you re-fill it with water or you will damage it. You may have a odor/taste water filter if so consult your operator's manual.
It takes an hour or less. Good luck.
Randy - Manhattan, Kansas
2015 Vista 27N
2016 Honda HR-V