[Gryphin]

Probably best to read this and my prior Posts knowing I had been picked on most of my life for being "different".
So, back to the question:
I think as in "Most" things. It depends.
That was beginning of the 9th grade, and I was 14. The year was 1969. I did not have to worry about knives or guns and such.
I did have to worry about becoming bully bait. As it is I got lucky. He could have been very seriously hurt, (this I learned later). My action was probably more an impulse driven by fear than some thought out strategy.

Generally speaking:
If you are in a non mortal situation
And If You can't back out
Strke first with no warning

If you are in a situation where someone might get killed do your best to back out.
Still I consider it a Darwin thing for an adult to be able to avoid such situations. Kids in school don’t always have this option to avoid these situations. You could be bleeding on the floor before someone with sufficient authority can intervene. I use the word “sufficient” because some teachers are unable to stop or breakup a fight.

Note: I generalize and "All Generalizations are False" (including that one).