they go in at the same time as my chiller.
on timers. I have a clock on my cell phone, it has an alarm function with labels. so I can either set up the whole brew day in there or more often I will set the alarm and then reset it each time it goes off. this way I can account for loss of boil when the chiller goes in, the propane runs out, or I decide I'm just too busy to drain the mash tun right this second.