I think you would find it better to do 3 short pips on the whistle for recall, 2 for turning (depending if you are quartering your dog) and 1 for stop. The stop whistle is effectively your brakes and needs to be 100%, start with the dog right next to you and blow the stop whistle and give the command sit at the same time, I start mine as young pups getting them to sit to the whistle for feeding, stopping at kerbsides on the lead and before letting them off lead. When your dog is doing this evrytime you blow the stop whistle you can then increase the distance slightly (always better at this stage to do it when the dog is coming back to you as you have chance to reaffirm with your hand raised to sit), patience in this excercise pays dividends in the end. Good luck