Check in is anytime really, I think it says 3-4pm but you can check in anytime and if your room is not ready the staff services will hold your bags for you in the back until it is ready. Check out is 11am.
I checked into the WL at 7:30am in Feb. My room was not ready, but I was given a card with a phone number to call periodically to check. I gave my bags to bell services.