choke-a-toke

I need some expert advice quickly. I have been a heavy smoker for 6yrs. I just quit smoking about 5 days ago, and I lit up again about 4 times this weekend. I just could not resist. During the past month I have been chugging about 1/2 gallon of 100% cranberry/blueberry juice per week, and 2 gallons of water a week. I am very fit, and have little body fat. I work out side as a landscaper and sweat daily, and work out lightly. I have also been taking about 250mgs of Niacin p/ day. I weigh about 150lbs. and I am 5'10" tall. I do not know what to do here. I might have a surprise drug test for probation on August 10th, when they let me off Mistermeanor probation. However, they have never tested me before. I am just worried. If I fail this test I will be encarcerated for 180 days. I have been thinking of buying XXtra-clean just before the test just to ensure I pass. I plan on not smoking until after my meeting w/ the Po.

Does anyone have any recommendations for me? Should I change or manipulate my regiment in any way? Are there any steps you guys follow to ensure a negative result?

P.S. there is no way for synthetic piss or taking in clean pee. They make you wash your hands and they watch your penis while you piss.