I have a pre-employment urine screen on Monday (tomorrow) and I do not know what time I have to go, they are just going to call me and let me know when so it could be several hours.

My plan is to collect my daughts clean urine and put it in a condom, place a hand warmer on my undies, and wear it till I get the call which could be several hours. I have been practicing this method and with a digital therm I get a reading of 94 - 97 and seems to cool quickly. With the forehead type therm I get a reading of 100. what is the deal with that? I am so nervouse about temp already. What should I do, put it in hot water till I get to the facility then "crotch it" (externally). Then cool it off it is too warm? Does the temp strip on the canister stay at the first temp it registers or does it register temp as it cools? Leaving it in the fridge is not an option, I will be at my current job and can not get home before the test. What to do, What to do?
So I have thought of vaginally carrying a 2 oz bottle, but how long could I keep that inserted considering that I have a few hours before the test. Would it maintain the exact temperature without having to warm it at all? or should I keep it warm someother way until I get close to the facility then insert it, how long will it take to become body temp? Please help me, I am so desperate. Thank you