It's really just a trial and error thing. Set your rack up and try the thermostat at 92 or 93 and keep checking temps for 2-3 days to make sure temps are holding and they're just right before moving all your babies into it. Once the temps have read right for a couple days I would move them all into their new home. Try feeding them in their current enclosure before moving them since they could go off feed because of a new environment at least they'll have a full belly!