What works for me is very similar to what Ian has described.

Make your turn 3 distinct movements and stop after each movement. Bring your club back to parallel with the ground. While doing this, you want to have the feeling like you are pushing your club away from your body. Next, cock your wrists to 90* and last rotate your shoulders. As this movement becomes comfortable, take the stop out between each movement. As that becomes for fluent, speed the drill up until you have reached a nice relaxed speed for a backswing.