Mouth Swab sometime this week, smoked last weekend!!! Help.

[Teto]

Last time I smoked weed was saturday night around Midnight. I called out of work today cuz I heard there is a mouth swab sometime this week. I am taking 1000MG of Niacin every 6 hours, putting peroxide in my mouth every 6 hours, and using mouth wash every 6 hours. I was wondering does Niacin work for a mouth swab? I used it in the past when I was in the ARMY for piss test and passed all of them. Am I doing enuff to pass the test if I was to go in tommorow which has been at least 48 hours??