There is a prevailing school of thought that the victim should be compliant until he's pretty sure a robber will kill him, such as taking him into a back room or in a vehicle. In this case, I think the victim has ample reason to believe the robber means to kill him, without any of the normal indicators. At what point should he start to resist, if at all?
I've seen too many videos where the victim DIDN'T HAVE TIME TO BE SURE OF A DANG THING.
He or she was just SHOT without any "ample reason", without any "indicators". In such cases, the victims' murders were probably determined in advance.
Starting the resistance when you have a gun to your head as you unlock your car or while in a 7 Eleven might be a bit late. It also might be your only chance, and no one on a gun forum can answer your question for you.
Just my opinion that may not be shared by all.