We're on our way to CSR next week for the first time - I know at the other resorts, if they have a room available for you at check-in, they get you right in. Otherwise, they will go ahead and check you in and let you know when the room will be ready. We've even gotten our keys at that point but told that the room wouldn't be ready until 3 (or whatever time it will be ready). If you have some time on your hands, you could head to Downtown Disney to shop, stroll the Boardwalk, walk around the CSR, hit the Pepper Market for a bite to eat, or leave your bags with the bellman and change into your swimsuit for a dip in the pool. Personally, our flight typically arrives around 1130 or 12, we get the rental car, DW has to hit Character Warehouse at Belz and that usually puts us at our hotel around 2-230 and we get our room right away.