If youโre getting drug tested definitely stop at least 1 month before you start, for your own peace of mind. I got drug tested for two different companies (two different testing methods) and had smoked a week or two prior but was hella stressed during. But yes generally the more you smoke the longer it stays in your system. The different testing methods have different time detections. For example a mouth swab can detect THC up to a week I think. Whereas a hair follicle can detect up to month(s)