What body area is it?
As you probably know, Laser can only kill follicles with anagen hairs (providing the settings are high enough, hair thick enough etc etc). So if you wait too long, some of the hairs may become telogen so this treatment won’t effect them.
I don’t know how long it takes for hairs to become telogen in different body areas, I’m sure the electrologists will know. However, if it’s a body area, I think you’ll be fine and most of the hair will still be in anagen.
The hairs that can’t be killed now (of any) will just need to be treated later when they come through again. So in any case it wouldn’t be bad, it would just require more treatments.