Warning shots are almost always never justified.
If you should pull the gun and then the trigger, you should be justified in shooting the bad guy. If you aren’t justified in shooting someone, the gun should stay holstered.
Waiting until you are justified in shooting before drawing is a bad idea in many cases.
The far and away most common defensive use is the display that stops an escalating situation. Elderly couple, or maybe your wife, alone, on the side of the road waiting for AAA. Creeps won’t leave after being asked repeatedly.
No weapons seen but just that 6th sense going off loud and clear.
A display of being armed can change the whole dynamic.
In probably 80% of the nation the people is question have no legal need to wait to get the gun until the attack begins, or until the suspicious person showed that they are armed.
Exactly how I was trained.