when is it "ok"?

[model 70]

home protection or otherwise. i've been racking this over in my brain alot lately. not sure why. when is it ok to pull the trigger? do they have to flash the gun? maybe a knife? not only do i fear the leagl issue but to me and most others, this is a BIG deal. you're quite possibley taking another persons life. i mean, i'm sure alot of home invasions, attacks and self defense shootings could be solved other ways since the attacker doesn't always have a gun. then again, if you wait to see a weapon it could be too late and i'll be damned if i'm gonna go out in my own home with a gun in my posession without taking a shot or two. what are your thoughts?