Y.B.I

Ive been on probation for about 3 months i give weekly/random drug screens, the test they use is a dip stick kind they dip a little stick thing in the cup of urine , any ways i am 18 weigh 119 about 5'7 im a skinny one . I smoked a blunt of some reggos between 4 people on friday night . i should have a drug test in the next 4 days , ive been taking 1000 between 1500 of niacin before i go to bed and ben drinking water since friday . my question is should i even sweat it or should i be doing some mad exercise in the mean while , any advice would be awsome thanks.