about 3 months and start out at 350f first round then 370 the second round after mashing up herb after the first round and then 390f for the 3 round if any is left after remembering to mash up disk again. i leave the fan speed on the lowest setting any higher and it will burn your herb..and you don't want that. let the fan do the work and don't pull to hard if your doing the direct hit.