Bring all three into the house and put them in the tub. Do not use the plug, but run the water until it is warm. Pick one bird up and hold its back under the faucet, and begin working the water into its feathers. Get the whole bird wet, but make sure to not let water get into its beak or nostrils. Put some shampoo on your hand and gently rub it into the feathers, add more water to get the suds going. Once the whole bird is sudsy, put the first bird down; repeat with the next bird, and then the third. Go back to the first bird and begin rinsing under the faucet. You can partially fill a bucket or wash basin with water and white vinegar to give a rinse that will get all soap out. With only three birds, you can probably use the same rinse for all. You can repeat this procedure with glycerin instead of vinegar to add shine.
I usually use a dog or cat flea/tick shampoo to kill any bugs they may have, and to kill any that they may pick up at the show.
After all birds are finished, wrap in a towel for a few minutes, then blow dry. I usually trim beaks and nails while they are wrapped in the towel.