I agree with Clamb. You must have hair growth in order to be treated with the laser. No hair root = worthless treatment.
However, I would imagine that between six to eight weeks would be a good time to get your laser hair treatment after your last waxing.
It takes hair about that long to regenerate a hair root. I’ve noticed also that my upper lip has hair growth in one week, my undearms, three weeks, and my legs, six weeks.
Since laser hair treatments are usually scheduled between six to eight week intervals, I think it takes that amount of time for the hair grow back in.
Also, the tech told me that I could wax the areas treated with the laser a day after the treatment, just to get rid of the hairs before the two week shedding period post LHR. Which makes sense to me, but I wouldn’t do it the third week post LHR treatment.
I know this is confusing, but the bottom line is to at least be able to see most of your hairs near the skin surface before getting your first laser hair treatment, that way you know at least those hairs will be treated effectively.