Be careful how yor feet are working. If you step across with your right foot to hit the shot, you will most likely be late. Learn to step out with the foot closest to the ball, show the butt cap at the ball, then pull the butt cap across you body.
All you need to do is get the butt cap behind the ball then hit. Nothing else. Your shoulders will turn naturally and be sure to step first with the foot cloest to the ball, set it, then transfer the weight forward with the racquet.
If you take a backswing and step across, the butt of your racquet will face the side fence. Big no-no for the onehander. Especially on the return of serve.
Former USPTA Teaching Professional
Volkl Tour 10 V-Engine Mid/Luxilon Big Banger