I just crack a heat pad about 30 minutes prior to puting it on the bottle so that the heat pad is fully warmed up then nuke the sub for about 10 seconds that should bring the sub temp around or a little over 100 degrees then put the heat pad on the bottle opposite side of temp strip and leave it there till testing and it should mantain a temp around 98 to 100 u will be fine even if it is a little to hot when it hits the cup you could blow on it a little and it will quickly go down its better to be a little to warm thn to cold because you can cool it enough in the bathroom you can't heat it up in the bathroom. If your time frame is going to be similar to mine for taking the test you will be fine even if it takes you a little longer hope this helps good luck