sorry, you have to reasonably assume you are in imminent danger. the 120 lb guy saying he's going to kick shaq's ass doesn't mean shaq is in imminent danger.
here's a summary of california law.
https://www.bajajdefense.com/california-self-defense-laws/
Establishing Self Defense
In order to successfully establish that you acted in
self defense, California law requires you to prove each of the following things:
- You had a reasonable belief that you were in imminent danger of suffering harm or death,
- You had a reasonable belief that using force was necessary to prevent such harm, and
- You only used an amount of force that was necessary to stop the threat.
Imminent Danger
Imminent danger means a threat that is happening right now at this very moment. Imminent danger must be current and immediate. Danger that is perceived to be an issue in the near future or at some other point in time will not be considered imminent.
You only have the right to justify the use of force or violence when danger is imminent.