One tip I have for jumpers is, turning is just as or even more important then going over the jump. You don't have fly around the arena at top speed to get a good time. Usually doing that results in missed distances and knocking a rail anyway. Getting good a turn is the best way to shave time off your final score. In hunters you make big turns and utilize the whole arena....if you use the whole arena in a jumper course you're time will not be a quick enough. Especially if your on a pony with a shorter stride and other people are on horses with a bigger stride. A lot of times in jumper shows the pony's are unbeatable, because they can make sharper turns then a big horse.
So I would suggest practice a lot of circles.
Good luck, jumpers are a lot of fun.