Try working on your release over cross-rails, if you're nervous. He won't take off as badly after a tiny jump as he will a big jump. Trust me, I know how nervous you are about giving that release and then having him just run away. LOL I've ridden plenty of horses like that. You may see he's more eager to jump (not speeding up eager, but relaxed eager) if he realizes that he won't get caught in the mouth over the fence. A lot of horses rush fences because they are nervous for one reason or another. If he starts to realize that jumping is pleasurable (ie. "Oh wow, now I don't have her holding onto mouth over the fence") he may relax more going into the jumps and coming out of them.
After your show, go back to some cross rails and small verticals (2' or so), look up different grid work you can do, put trotting poles in front of jump too to keep him from speeding up. A great book you may want to pick up if you can is "101 Jumping Exercises: for Horse & Rider". :) Oh, and like I said earlier, if you don't know how to do them already have your trainer work with you and Indy on teaching you two half-halts. They're awesome for a strong horse over fences! Hehe.