Don't forget....don't touch your dog until you get the bird from him. You don't have to have him sit in heel. He can come to you and you can take the birds from him.
After you signal the judge to have the birds thrown, you can't talk to your dog, until the judge calls your number. Then you can release him. Praise as much as you want on the way back.
Some clubs do have live fliers in Junior. 2/5 junior tests that I was in this year had them. In general, they save the fliers for the higher stakes.
Don't let your dog pull you to the line. He has to be under control.
Those are the main things you need to be aware of so you don't inadvertently get DQ'd.
Bring a whistle! Don't wear white or light colors!