My experience was a month ago so may be stale, but we arrived 30ish minutes before opening and were let in far enough to rent a patio (which is why we got there early - we were hoping for a walk-up reservation but they were sold out for the day, got a clam shell instead), get a locker, restrooms, etc. They held people at a couple of spots from going further in the park until very close to 11, maybe a minute before, if that. Was a very easy and smooth process.