Yes you can check in early. I have never had a problem doing so.

Actually, check in is 2pm.

I have checked in a bit early before. Even if they don't allow you to for whatever reason, there is a very large staging area for you to park until you can check in.

Yes, earlier check in is allowed. The staff there are very friendly and helpful. There Is space to park and wait for your site to empty also.

They will let you check-in anytime after check-out. The first time we went they even went to the site to enforce check-out on a camper that didn’t leave on time.

I was last there in March/April 2018, so situation may have changed especially with COVID protocols …VERY busy campground, typically a line of campers awaiting checkin. At the time I visited, if the prior occupant had vacated you were allowed to proceed to your reserved site. Good luck.

It is a big, busy park that is almost always full. I doubt very much they will let you in early,

It is followed to a y. They will have you line up and not start letting you even check in until 4. You also need to be gone on time or the ranger will come to your site and pack you up.