If your dog is antsy on the start line, or anticipating their release and breaking their stay, there a number of homework exercises to work on. These are things that will help the dog rehearse the self control that is needed to hold their start line stay in agility. This video link will go through a number of examples - https://www.youtube.com/watch?v=QgSgGJZDajc&feature=youtu.be
Clip #1 - Crate Games
Crate Games is a DVD and training philosophy by Susan Garrett, this is a real brief demonstration of two key elements.
1. Stay in your crate while I open the door, wait for me to release you. Wire crates are great for this because you can reward the dog through the top of the crate while you work on slowly opening the door. If you have a solid or soft crate, you need to feed the dog through the opening of the door. Slowly crack the door open, and reward the dog for staying in the crate. If they try to get out, close the door...always keep one hand on the door in the beginning. Challenge the dog by adding distance...walk away, run away, come back and reward. If they come out before you release them, I say nothing walk closer to the crate and wait for them to go back in...then start the exercise over again. If they don't go in on their own, take them by the collar and help them in. If they fail more than twice, you are making it too hard...you need a quicker rate of reinforcement.
2. Offering to go back in the crate on their own. I always reward after the release cue for the dog exiting the crate. If I am standing close to the door will he chose to go back in on his own with no prompting from me? You'll see Chip do that in the video, he knows getting in the crate is how he earns his reward. You might have to wait a few seconds to see if they'll go in on their own. If this is brand new to them, you can toss cookies into the crate to help them go in.
Clip #2 - Transferring Crate Games Ideas to Dog Cot.
Instead of a crate, we give the dogs more freedom and ask for the same behavior on a dog bed/cot/plank/stool/mat (or elevated is easier). I ask him to line up and sit, then build distance and duration away from him. I can also add in some distraction work - proofing that he won't try to leave the cot to get a cookie out of his reach. Extra video example of working the 3 D's - Distance Duration Distraction
Clip #3 - Wait To Go Outside.
One of the best places to practice self control, is not bolting through the back door to go outside. I will slowly open the door, and if he gets up I'll close it. You can reward with cookies when they hold their stay. But ultimately the reward will be getting released to go outside. Can you walk through the door first? Then give a good release cue, just make sure they are still sitting!
Clip #4 - Waiting for Dinner.
Can they hold a stay while you put their bowl on the ground? If he gets up before I release him, I just pick the bowl up and we start over.
Clip #5 - Crate Games in the Car.
Same idea as above, he needs to wait with an open door for me to release him. If he tries to leave early, I will just close the door.
All of these concepts are basic Premack Principle (the idea that a dog will perform a less desirable behavior for the chance to do a more desirable behavior. The more desirable behavior in turn reinforces the less desirable behavior). Sitting at the back door = getting to run outside. Sitting for your meal = eating dinner. Sitting at the start line = getting to run agility. Stopping in your 2on2off contact = getting released to run more agility.
Try to find as many possible ways to help your dogs practice self control every day!