They begin letting you in before 8am (depending on your reservation time) to at least 20 minutes before rope drop (9am in this case) since CRT and Crystal Palace begin reservations at 8am every day. There is a special entrance for this and you will have to give them your name to confirm the reservation before they will let you in (it is a good idea to have your confirmation number with you just in case - although I have never had a problem where I needed mine).
The Rapunzel meet in greet is where the old Story Time with Belle was located, so it is very close to the castle. But if your reservation is at 9am, you will not have time to stop and get an autograph because it is an experience (not just an autograph meet and greet) and takes about 30 minutes. Eventually they will make Rapunzel a regular meet and greet, but I haven't heard of it changing yet. You will want to wait until after your breakfast to get your photo. CRT may hold your reservation for a few minutes, but 30 minutes is a bit too long.
Hope this helps.