Well, the first thing you need to do is realize that scooting is breaking a stay. A stay means remain where you are, don’t move until released, right? Scooting is moving, so the dog isn’t staying.
Next, think about why your dog is breaking his stay. Is it rewarding for him? You bet!!!! each… little… scoot… gets him that much closer to the two joys of his life – you, and agility.
Now, there are two options; work on a running start with your dog, or retrain the stay. Maybe use a totally different command, since this one’s now meaning ‘scoot forward’ for him. I like ‘wait’, personally. Train the new word as an entirely new concept, with treats, rewards, and fun. Don’t compromise his stay behaviors, though. You don’t want him to move out of position at all. If he does, don’t let him have his reward. Train your boy that the only way to get to his agility is to wait. He’ll get it, I promise!