Luckily mine are older although this thread has reminded DD to pack some treatment for uni apparently they often have them go around in the first year.
Both my DD have dark curly hair and we had a nightmare until I got into a routine.
So first thing is a silicone based treatment or suffocates them so they can't become immune to it.
With their hair we never stood a chance of getting all the eggs so whilst I combed to get the dead lice I didn't do it to get all the eggs.
Them the important part of retreat their hair after 5-7 days to get any newly hatched lice.
Them treat again in another 5-7 days, usually the 2 treatments would work but I'd still go for a third just in case.
Then hair monitoring I used to visually check their hair ( which is what my parents did when I was little) but soon realised they'd become infested before you saw the fuckers so I switched to every Sunday coming through with a nit comb with conditioner too check for lice.
Some people I knew combed their kids hair everyday with a nit comb but as you can imagine with curly hair that would have been horrible for them.
Good luck OP I don't miss those days, oh and tea tree or other preventive spray don't work I'm sure the boys just laughed at them 😉