Your line of thought is OK, just remember, sometimes people are confused and might be in some kind of mental state that they think they are where they are not. In other words be sure the person is a danger before you do something to defend yourself. Ie. what if it's the paper boy who just got hit on the head and does not know where he is.
Danger means forcing your way into our house, getting past the dog and going down the hallways... shouted warning and then pray and make the best decision.
I think IPSC for pistols and skeet are a good way to train for this kind of thing. My kids love it and it's a lot more interesting to shoot a swaying, spinning and moving target. Ammo ain't cheap but it an activity that we can do 1 or 2 times per month. The boy loves it and the girls have confidence that comes from mastering a martial art.