Should be one directly under the basking light... or lights I suppose in this case. It's hotter directly underneath, otherwise it may be too hot or too cool and you never know.
For ease you might want to consider getting another, for now you can just put the probe under one and leave it there for 30 minutes to an hour and make sure the temp is at a good range for the age of the dragon, then move it to the other and do the same check.
Will be looking forward to seeing them!
. That's kinda what I was wondering if that's what Shorrie was talking about.Reading these posts, I think you 2 are confusing each other between thermostat sensors & thermometer sensors
Personally, I have never used one, but thermostats are good if night heat is required because the night ambient room temps drop below the mid to low 60s F (17C) to control a CHE (Ceramic Heat Emitter). But for daytime or Basking Spot heat, I wouldn't use one to control the Basking Bulb. Once the proper temp is reached it would shut off the bulb, once the temps drop a certain amount, it would turn it back on. The Basking Bulb would be going on & off throughout the day, like turning the Sun on & off, which in my opinion does nothing but confuse the BD.
The majority of us simply play with the distance & wattage of the Heat\Basking Bulb from the basking spot until the proper temps are achieved in our normal ambient daytime room temp. Once that is found, it should not have to be adjusted much at all after that, but still should be monitored.
This is a CHE (Ceramic Heat Emitter) - screws into a regular light socket (Should be a porcelain or ceramic socket) & provides heat with no light emitted. Generally used for night heat if the night ambient room temps drop below the mid to low 60s F (17C).
That is what the packaging & advertising calls them, so for people to be able to find what they are looking for, that is what we call them. 
" moments, so don't feel bad.
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Don't feel bad....I never hard of a CHE until joined this forum....lol....
