They really need to be cleaned off the same day to avoid the risk of ruined paint. If you wash them off the same day, it is pretty easy, and water works best. Leave them on to bake in the sun for a day or two and it can be a real bee-yatch to get them off...plus the paint damage. Lots of vehicles running around FL with paint damage from the little buggers.
They weren't too bad today, and I can vouch for your advice. I waxed the front (well, not wax, but poly) and they washed off easily with water.
Still, it's disgusting when they are so thick you have to pull over and scrape the mess off the windshield just to see where you are going.