When are you arriving...?
You probably already know that you can forget about today and tomorrow. (4th weekend).
Otherwise, as with all first come spots, it's up in the air. Some folks like to leave early, others just after lunch. You take your chances. But, we camp a lot on the Oregon Coast in the State Parks including Cape Blanco and from now until mid September, all I can say is good luck.
"If we couldn't laugh we would all go insane."
Arctic Fox 25Y
GMC Duramax
Blue Ox SwayPro