When to draw

Depends on the situation's specifics and dynamics, of course, as to how soon a given citizen justifiably feels sufficiently threatened such that bringing force to bear is the right answer.

Depends on the state's specific statutes, as well, as to what particular legal justification exists. Generally speaking, the "reasonable man" standard applies, in which it's on the citizen to gauge the point at which a reasonable person should be every bit as concerned over impending loss of life and limb.

But when it does come to that point to where you're legitimately at risk of loss of life or limb, at minimum at the point when you legitimately fear that loss, you have every right as a citizen to take the gloves off and halt that threat to you and yours. If merely going for your gun does it, great; if drawing, fine; if it requires firing, so be it. If you can get through things without those steps, then you've won the holiday turkey. But the last thing you want to do is to blow the call so badly, or to be so afraid of ramifications of taking legitimate steps to protect yourself, that you're frozen into inaction and hesitate. Such hesitation can easily get you killed, situation depending.

If concerned about when, how much, how to go about it ... consider a series of CQB type force-on-force training, in which you're challenged with various hands-on, hand-to-hand, knife, and gun defensive situations at closer distances, ones in which your opponent has every intent and opportunity to harm you using whatever contrivance, subterfuge, speed or degree of violence can most likely get the better of you. You'd be surprised how quickly that little "line in the sand" can change as the dynamics of a situation blow sideways. The more training you can get along these lines, the better.