Niacin and Drug Testing?

I have a court date on Friday the 11th of February and have a joint I want to smoke. I have been taking Niacin 500mg a day for 3 days now and am going to continue that regimen. I do not smoke often. The last time I smoked was over a month ago. If I smoke right now (superbowl day) and take the Niacin, will the THC be out of my system by the court date? Honest helpful answers only.