What is the appropriate time to pull the trigger?
I've never had to shoot in SD, and can't claim to be an expert, but it seems like anyone who ever had to pull the trigger made that decision on their own.
In my state, the same rules apply to a car as for your home--at least where a criminal attack like the attempted robbery you described is concerned.
Of course, all his buddies would have testified that he just wanted a ride and meant no harm.
I wonder how many of these "go ahead and shoot me" guys would feel that way about a .40 S&W gender alteration and testosterone adjustment?