Good. If you believe you have the time, ability to fire a warning shot than you call into question that you were in fear of imminent threat to your life, or great bodily harm.
Second. You’re responsible for every round you fire that comes out of your weapon. Any round with sufficient penetration (as defined by the FBI) will go through most dwellings walls and therefore a threat to those on the other side.
Third. The person you’re trying to warn can consider themselves to be in fear of imminent threat to their lives. Even a burglar has a right to self-defense, i.e. if he’s just grabbing your stuff and not a threat to you, you don’t have the right to use lethal force and he now has the right to defend against your attack.
Fourth. Unless you’re well trained, the head is a difficult target. Get some training, you fire at center of mass until you assess the threat has stopped.
Fifth. Good site to understand timing, how quicly things happen. Materials from these sites are used in assessing whether police shootings are justified at boards of inquiry. It can also help you understand that action beats reaction. Compare officer motions to subject motions and interactions.
forcescience.org/demos.html