Quote Originally Posted by Cyclonite
Never ever use you first piss of the morning
When youre taking a home test to see if your clean (not to see if a dilution technique is doing its job), you ALWAYS use the first void of the day when the concentration of THC metabolites would be at their highest. If you pass with the first void of the day, you'll pass the lab U/A at any time.

Now if youre taking the actual U/A, then yes, urinate as much as you can, and if possible, try to schedule the test for the afternoon.