Just don't shoot to kill (at least not on the first shot) unless they've drawn a weapon.
There's no winning that game. Then it'll turn out to be a toy gun. Or they were just trying to scare - they weren't really going to shoot. Then the argument will be "Just don't shoot to kill unless they've actually fired in your direction."
I know this is again going OT, but the stand your ground laws in Florida permit deadly force anytime the victim believes their life is at risk. That's such a subjective definition, that it really comes down to the investigating department and the DA whether they agree or not. Waiting for an assailant to make it abundantly clear that he intends to kill you is not a strategy I'd want to take - as by the time you figure that out, it's too late.
For example, if you're a 70+ y/o senior who is approached by a 30-something guy who is foaming at the mouth in anger and throwing things at you, do you wait for him to land the first punch? If so, at your age, such a punch may well be the end of you. Never mind not knowing the skill and training of the assailant. Keep in mind that's exactly what happened to retired TPD officer Curtis in the movie theater. He didn't wait for the escalation to come to blows (though he was hit in the dark with a cup of popcorn). The younger guy was climbing over the seats to engage. His wife was trying to hold him back when Curtis fired a single shot (through the wife's hand) into the guy's chest - killing him.
I'm not particularly fond of the police profession - but after watching the video of that shooting in the theater, I really have to side with Curtis. If he had waited, it may have well have had the opposite outcome.
It's not an easy decision, but choosing to be victimized and letting bad people walk all over defenseless victims is not the answer either.