I agree with watching what you say on public forums. With that said, we must remember that Castle Doctrine only means we do not have a duty to retreat from our homes and, in some states, businesses. That does not give the right to assume that everyone trying to break in is going to attack you and therefore give you the right to take their life. You must still identify a threat to life or grievous bodily injury before pulling the trigger.
Remember also not to use arbitrary measurements like "within three seconds" as a person can close a distance of 21' in less than 1.5 seconds and your adrenaline will make it very hard to estimate time. You also never want to take your eyes off of the intruder for any reason like checking your watch.
Do not try to determine an intruders intentions. You cannot read his mind and have no idea what he originally intended to do nor what he will do now that he faces you. Criminals learn early on to play on your sympathy with sob stories. Give commands and expect them to be obeyed immediately. Allow no talking or negotiating or stories. Use solid, short words that are easy to understand, such as:
"STOP! On the ground! Spread your legs! Hands out! Palms up! SHUT UP! Police are coming - they will talk to you!"
Any command that is not followed immediately should be followed up with "i will shoot! Do it NOW!". These commands should be part of your training with a partner, as well as both compliance and non-compliance by your "suspect.". Training makes you sound more authoritative and believable. Meek, quiet types should practice with a gregarious extrovert to see how it's done.
Call 911 as soon as possible and don't hang up! If you call when you hear the glass break and the tape has all of your loud, simple commands on it, you will have a record o how you tried not to take his life. Obviously if he is right on you or drawing a gun, then you must make a decision to fire. But everything you can do to prove you tried not to take a life and it was only done in the gravest extreme will help you and your family avoid trials, court costs and civil suits.
Castle Doctrine or not, it is better to save yourself and your family from the psychological horror of a dead body in your house. Send the kids to Harvard instead of a $100,000 legal defense (which is considered average in a shooting). We have a duty to protect ourselves and our family, but we need to practice and be ready for the proper way to do it.
“Malo periculosam, libertatem quam quietam servitutem." (I prefer the tumult of liberty to the quiet of servitude.). Thomas Jefferson
"All that is necessary for the triumph of evil is that good men do nothing."
-Edmund Burke, Loosely translated from Thoughts on the Cause of Present Discontents. (1770)