One concept that sets Krav Maga apart from most other self-defense systems is that we consistently train from a position of disadvantage. The belief is that all techniques must work whether we are prepared or not, as most situations requiring us to defend ourselves occur suddenly and with little warning. If we only trained from a prepared position (our fighting stance), we would either be delayed to action or—much worse—freeze when caught off guard.
Part of our training involves practicing both offensive and defensive techniques from what we call passive or neutral position. Beyond developing lighting-fast reaction, not much forethought must go into defensive techniques; the decision to act has been made for us by the attacker. Launching a preemptive assault, however, is a very different situation. We must consider the how?, the when?, and the what then? (the immediate and longer-term consequences) of such an action. Regardless of when you choose to spring to action, you will most likely be doing it from a passive stance.
I’d be remiss if I didn’t inject a short disclaimer here that a preemptive attack may open a barrel of legal consequences, so these techniques should not be used haphazardly. The first and best defense is always avoidance, followed by escape. Only when danger is imminent and there is no escape should you preemptively strike someone else, especially with these very powerful techniques.
In a nutshell, you must decide at what point when is now, or what the trigger is that will make you launch a preemptive attack to diffuse a souring situation. Is it a certain tone of voice or something about a person’s body positioning that will tell you it’s time to fight? Or should you wait until the other person makes a physical move towards violence? When is when? There is no correct answer other than “before it’s too late”. This obviously varies by situation and by individual. Also be aware that acting too soon may very well worsen the situation if there’s a chance for verbal deescalation.