The time frame was about 30 minutes nctar...i just heated it up for a few seconds the strapped the pad on the side opposite the temp strip and popped it in some whitey tighties that I wore to the testing site...im sure it would have kept it up to temp for another hour or so even...when i took it out it read right at 98...its not hard and i didnt even practice it...just be cool and don't attract attention to yourself and ull be fine