1) Dolphin feeding: As soon as the park opens at 9:00. There is a 9:30 feeding and its located near the park entrance. Dolphin feeding is very popular so it will get crowded as the day goes on.
2) Manta: This is the first roller coaster you will see as you enter the park. This is a very popular ride so get there early. I would do either Manta then Dolphin feeding or Dolphin feeding then Manta.
3) Any show before Noon. Shows before noon all less crowded than in the afternoon. This goes for all shows. Usually 10:00 Blue Horizons Dolphin show, 10:45 Pets Ahoy, 10:45 Clyde and Seamore Take Pirate Island and 11:00 Shamu show, One Ocean. (If there is an 11:00 show. Sometimes the first one is noon or later which tends to be packed)