Let's break this down

As long as I had a weapon

infinite

The fucks a fifth grader gonna do? And you can just dropkick the second graders.

Am i allowed to kill them or am i limited to just knocking them out?

All of them

Realistically I'd say 5 waves till I got tired and just wanted to lay down

Literally all of them. Unless you pass out from exhaustion, then they like, piled on you. Then the waves would just keep increasing and eventually the weight would crush you.

Do I have time to snack between waves?

Build a base off the ground, let the waves pass and have a bow with me so I can take them down in my own time. Strats

You would run out of kids before I broke a sweat

I'm never too tired to beat children.

Idk I'd probs get tired after the 10th or 12th wave

about 20 waves