What circumstances do you define as appropriate for a concealed handgun be drawn?

What circumstances do you define as appropriate for a concealed handgun be drawn? 

For example -.. If a man is twice your age and is coming at you with some kind of sharp, or blunt weapon -.. It's justified to draw your handgun and aim at him.
You can also draw your handgun on a group of people coming at you, threatening to kill you -..
Or - If somebody generally begins to beat you for whatever reason, then it's justified to pull your handgun on the man.