if you smoke once a week...3 days your good.
heavy smoker you wont pass
try synthetic urine.
I did a flush from GNC 10 years ago for a job interview...smoke 4 joints a day..I passed...someone else took it 2 years later and failed..
If they are following protocol, no. The big labs,Qwest and Labcorp follow protocol so they can't detect synthetic urine. But there are a couple small local labs that have tested it for being synthetic, but they are rare.