THE FINAL STEP
The final step in this exercise is to let the dog flush the bird when it is free hunting, just as it would in a real-life situation. Ultimately you would want the dog to stop/sit just to flush without a whistle command, and you would only use the whistle as an extra brake in case the dog decided to move on the flush. This is a huge temptation for a dog and hopefully you will appreciate how important it is to ensure that each and every step is fully learned by the dog before moving on. I would highly recommend the help and guidance of a professional trainer in getting your dog steady to the flush of any game, as they will have the experience and the facilities to help you succeed.