They say it takes three days to get out of your system if your a first time smoker ( smoked my first time saturday. Been looking this shit up. >> ). So technically they said, if you let three days pass and a week of extra detox after that, technically your system would be clean next time you smoked.
So 19 days should be good... Hope you drank alot of water before the test... I'm drinking water and cranberry juice like nuts for a drug test friday.