A lot hangs in the balance during those few seconds prior to shot execution. Your pre-shot routine should be enabling you to get aligned correctly with your target and mentally ready to play the shot. That means, shot planning, movement planning (practise swings) and entering a state of complete congruency and relative automaticity. If you are in any doubt or confusion during this time then the chances of hitting a good shot diminish greatly.
Achieving good set up posture will afford you the best chance of achieving your full range of rotation while moving in balance. If this area is sloppy then you are at a disadvantage before you start.
You will be continually adjusting and refining your swing in an often unconscious process of self-organisation (see Motor Control section). This whole process is centred around your connection to the club and control of the club face. Therefore, every micro move in your swing will be affected by how you hold the club.
This area of your game needs to be systematic. There are enough variables in the game without your setup being another. Be mindful when setting up and check with alignment aids on a regular basis.