For the just incase moment when you have the cup they ask you to pee in. Start collecting after you have already started peeing. The highest concentration of thc in your urine will be at the beginning of the stream.
It is also a good idea to use the restroom a few times before you get called and tested while you are in the clinic.
updated by @goldeneagle: 07/23/15 03:41:58PM
