You shoot until the threat is no longer a threat. If you shoot once and they turn in retreat, the threat has been neutralized and it would do you good not to fire any more rounds and call 911 and your lawyer. It's obviously a self defense scenario but its very hard to prove self defense when someone has several rounds in their back. Place your weapon away from your person, stand on it if you have to. "I was in fear of serious injury or death" for yourself or whomever you are defending should be your first words to any LEO that arrives on the scene. Remember, "serious bodily injury or death". I will shoot to defend myself, my family, and anyone around me...but threat recognition and knowledge of your laws are the main things. It's easy to say "I'll shoot anyone that enters my house unwelcome" but a lot harder to defend. I know in TN, you can't use deadly force to protect personal property unless as I said before, the bad guy gives you reason to believe he might want to cause serious injury or death to you or your family. Threads like these are great for second guessing yourself and self evaluation, but what I consider even more important is knowing laws of your state. Anyway, I'm not a lawyer, but I have played one on tv, and I'm no one to give anyone else legal advice