If you just want to scare someone away, your gun should never leave its holster. Most confrontations can be resolved by keeping a clear head and talking your way out of it.
However, if you find yourself in a truly life threatening situation, all you will likely have time to do is draw your weapon, unsafety, and pull the trigger. Any hesitation can be the difference between you or your attacker lying on the ground. Many people who carry concealed weapons do so with a full magazine and a round already in the chamber because thatís how fast things will be happening.
Waving a gun is just giving your attacker more time to figure out a proper way to overcome your defense. Lives are saved by the element of surprise. You draw, you shoot. Anything else is only putting you in more danger.