When I start to jump ahead, it's because I start riding the fence instead of my horse. When I get so focused on the fence ahead of me, and I try to get to the fence, instead of allowing the fence to come to me...that's when I start lurching forward.
I focus on what is ahead of me, instead of what is under me - my horse...who is the most important factor here, not the fence.
Ride your horses rhythm. Focus on your quality of ride between the fences first. Balance, rhythm, straitness, control. Remaining balanced over your feet, functional two point. Staying over your horses center of gravity - balanced - and learning to remain ontop of your horse.
It's not your job to jump that fence - I know it's easier said than done - but that's your horses job. Your job is to get the quality of ride between the fences, and the fences will take care of themselves *your horse will beable to do its job at the fence, if you ride correctly between them*.
So - when you focus on what is under you, instead of what is infront of you, you will learn to allow your horse to do its job, while you remain over your horses center of gravity - allowing the fence to come to you, instead of you rushing to it.
Here I am anticipating the fence...trying to rush my horse to it - instead of allowing the fence to come to me...
I end up jumping ahead.
And the 2nd approach, this time I focused on my horse, staying over him, rhythm and balance...and forgot all about the fence...
I did not jump ahead. I stayed over him.
Does that make sense?