Hi! I would book ASAP, popular places are selling out fast. I booked most of our campgrounds/hotels about three months ago. Keep in mind some National Parks are requiring additional passes this year or limited shuttle tickets just to get inside parks due to covid. Some of these you can get 60 days prior, though some are 14-days prior. Check websites:) Definitely start booking more popular parks like Yellowstone, Yosemite, Zion, etc . first bc I had to plan trip around these dates since limited availability during our trip time. where in Pa are u from? We are in the Pocono area. Have a great trip!