How Soon A Person Has To Stop Smoking Before A Drug Test?

hi, i have a urine test today. i smoked with my mates nearly everyday from new years to march 30th. ive been clean since other than a few tokes on a joint last wednesday. I am 6 ft 3 and weigh 80 kg, and i go gym 2/3 times a week. have i got a good chance of passing? I read that the stuff from before (new years) takes up to a month so that should be out of my system and the one off joint takes up to a week which should be fine shouldn t it?