The time can vary a lot when cooking up Creepy Crawlers. It depends on how hot your Thingmaker gets and how big of a mold and how much plastigoop you are putting in. For me the best way to tell is by watching for the goop to go from a cloudy to a more solid color. Once you try it once and watch you will see and be able to tell when the goop is fulled melted. Another good indicator is when the smoke starts. Now if your Creepies pass the rip test then they are full gelled (cooked). Only try the rip test on room temp Creepy Crawlers since the hot ones will rip much easier. So once they are at room temp see if they stretch and flex like rubber, without breaking. If they are not cooked all the way you might put some fresh goop on the rip surfaces, put it back in the mold, and re-cook it. Let us know how it goes and if you have any other questions.