What he said. Do be aware that you cannot expect to drive as far each day as you can in a car. For starters an RV does not handle like a car, and for safety's sake you will want to go slower. You will also want to stop for the night well before dark, so your driving day will be shorter. Backing into a campsite in the dark in a place you've never been before isn't especially desirable. Plus, campground offices usually close by dark, if not by 5:30 or 6:00 pm. When we travel by RV, we plan on 300-350 miles a day max. And there are many who say 200-250 miles a day is even better.
Since this is your first RV adventure, don't feel bashful asking for help and advice from neighbors at the campgrounds you visit. We're a friendly bunch, the odd curmudgeon not withstanding