I wanted to expand a bit here. I think it is CRITICAL that you get the dogs nuts about birds. If you have gotten this far, then add the gun. The key is to have a person throwing live birds that are bouncing and flapping, so the dog is totally tuned into the bird. Only fire when you can see the bird, and the dog. The dog should be totally focused on the bird. Then, GRADUALLY start to fire when the dog is closer to you, and farther from the bird. When you go to quail, just dizzy then a little and toss them. Ideally the quail will fly a ways after the dog started to chase, and this is when I switch from the 22 to the 20gauge. Same holds true in the transition to a 12.
When you start to hunt, put the dog on the outside of the blind, and put your body between it and the gun. Also, start with only one gunner. Have that person shoot the first bird that the dog is watching, even if it is not a prime time species. After three or four times, I think that you will be safe. What you really want is a dog that associates the gun and the birds in a positive light. First hunting trip is a key transition, along with those from 22 to 20 to 12.