Quick Fix?

Hey guys! I smoke Marijuana and take hemp oil almost every other day for my anxiety. I have a drug test coming up and I purchased Quick Fix synthetic urine. Im kind of nervous because this will be my first time using it and I have a few questions. Do I need the hand warmer? Some people said your body heat will do just fine but the urine comes with a hand warmer to attach to it. I want to be sure that It stays the right temperature. Where do you hide it? & how long should I keep the hand warmers on? Any info from you ladies would be great! Thank you