I'd say it depends more on what part of the hair they test. the follicle is tested for here and now but they can and a lot of times do cut the hair into 1/4 inch pieces and test them to determan a timeline of last use by using what science already knows about hair growth. I hope you get the job But you do still need to be worried, might consider a trim up above the collar just to be safe if it were me. GL.