ACLU: Self Defence Is No Excuse For Abusing A Thug's Right To Murder

Imagine this senario:

Jack constantly says he will kill Joe, because Joe has no right to live. However, Jack could not kill Joe, because Joe was the stronger.

Then, Jack started escalating his threats against Joe while finally building a weapon that could kill Joe.

Question: What should Joe do?

a. Wait for Jack to attack and then fight back knowing both will be killed.

b. Attack first before the weapon is complete and reason do so is self-defense.