I don't recall exact times, but the bus leaves HRH 2-3 times each morning, and makes pick-ups twice at both Sea World and Wet n Wild in the late afternoon. You can get a schedule when you check in at the concierge desk.
Now, when we were there, we missed the bus to Sea World because the first bus driver hollered out "This bus is for Wet n Wild only". O.K. we assumed there would be another bus for Sea World. Well, after waiting about 1/2 hour, we went to concierge to ask. Turns out, that was the bus going to Wet n Wild first then on to Sea World. We ended up just taking a cab to Sea World.
Upon returning to the HRH from Sea World, we caught shuttle at 4:30 p.m. Now, we get all the way to Porotino Hotel and the bus driver says "Oh, sorry, I forgot to pick up the people waiting at Wet n Wild". "I must've had a senior moment". He proceeded to turn around and go back to Wet n Wild without letting any Portofino guests off. Whatever. We just rode on....
My point is, ask the bus driver directly where you are going before you get on any bus! Then, keep your fingers crossed.