Recreation.gov posted some tips to help book sites for campgrounds and get the days you want. I already alluded to this in a previous post.
With as busy as US National Parks are getting it’s more important than ever to plan ahead if you want to be in park for your photography trip. It’s a good idea to lock in your campground first then plan your trip around that. There are usually alternatives outside the park or in nearby cities but they can add travel time to and from the park. And for limited access prime photo locations like the Cables of Half Dome, The Wave, or The Subway of Zion there is no alternative. Lock in your permit first then build your vacation around that date.