@Terpenetime linked the document I was talking about above (along with a couple of other useful things), and I was a little off in what I remembered about pre-heat times. 8 seconds is the longest recommended, but you shouldn’t damage anything until more like 15 seconds. Glad there’s more leeway there.
“But be cautious, a lengthy pre-heat time of more than 8 or so seconds is not recommended, this will only overheat the module and surrounding wood.
Permanent Damage may result from holding down the fire button for extended periods (more than 15 seconds) WITHOUT any airflow. The airflow through the heater keeps the temperature in the optimal range. Without airflow, the temperature will continue to climb until the heater module or wood is damaged.
WITH airflow, you can safely hold down the fire button for as long as you want, so long as that airflow is adequate enough to keep the heater in the correct temperature range. With the standard - Low heat module, you should hold the fire button down for the entire duration of your draw. You may even want to hold the button down between draws to keep the module hot, so long as you don't hold it down for more than a continuous 8 seconds WITHOUT airflow.”