I've read varying information, but if you smoke about a j or 2 a month it only stays in your system (urine) for 2-3 days. If you smoke atleast once or twice a week it will stay for about a week. Once a day smokers need about a months time to clean up.

Smoking 4 puffs from a j will more than likely clear within a day. If you're way paranoid just drink some water the morning of your test that way your urine will be diluted.