Just keep this in mind:

If your home test shows a positive with the first-day urination, and your scheduled U/A is 3 days away, then all physical activity should be curtailed until the U/A is over. You want to be as dormant as possible for those 3 days to prevent a bunch of THC metabolites from being released back into the bloodstream (as the result of fat cells being burned), which will all end up in the urine to be detected.