My thought is to treat the opponent's shot like a starters pistol and as soon as they hit the ball, I need to burst toward the hitting zone. That includes a partial turn along with partially taking the racquet back. The sooner I'm in postion and ready to hit, the more stutter steps and small adjustments I can make, and the less rushed my shot can be. That's when I can hit my best strokes.
I'm not much of a fan of Venus or Serena, but they both snap the racquet back as soon as it's hit by their opponent and that makes it almost impossible for them to NOT be ready to hit an incoming ball, even if it's a screamer.