Anytime there is someone in the office, 8am-9pm.

We are there now. Campers can arrive as early as 9 am and leave by 2 pm. Let the office know by noon if you are staying an extra day.

It’s first come/first served. In my experience, people are generally gone by 11:00, and just observing arrivals, it seems like they get there at all times.

Since it is a first come/first serve campground, all campers must checkout or renew by 2PM. We arrived at 11AM and were told we could go pick any open site. Hope that helps.