The earliest PS for Cindy's is 8:05AM. I've had an 8:10AM ressie and have finished and been out of Cindy's before rope drop, when the park opens at 9. At that early hour, the food is served fast, and the restaurant isn't completely full, so the Princesses make it around rather quickly. They usually all come out around 8:30, and can make it around the room quicker, since it is only half full at that point.