okay so how do i pass a cotton swab test??!

okay i just smoked at like 12 then i thought hey why not apply for jobs online so i get on monster jobs and apply at a place called accountabilities in fairfield....and not even 30 minutes they call back and scheduale an interview tomorrow which includes an interview, application, saftey video, and a drug screening test!!!
i'm assuming it's cotton swab since i'm doing it in the same office.....being as i smoked at 12pm(bammer not even high anymore) and my interview is tomorrow morning at 9am?? what do i do?? please no answers like your fault for smoking, your an idiot for doing drugs, because honestly i don't need to be lectured i'm a grown *** adult. Plus only answers that will work. thank you!(: