It hasn't gone up on temperature yet cause I just put it under.... but this is the right way right? The tortoises top shell should be about half the size of this temperature gauge. And it is directly under the heat lamp.
I usually lay them flat on their back on top of a brick or 2x4. Let it bake under the lamp for an hour or more. If the temp is too high after a few minutes, you know you need to raise the fixture up. No need to wait longer if it over heats in the first few minutes.
If you are going to use coir, you need to hand pack it firmly.