It's hard to understand the question...
The eggs have to be at a certain temperature AND humidity. That's the purpose of the incubator... to maintain this environment.
I have more experience with snakes, but there are quite a few things in common. First off, once the eggs are incubating DO NOT rearrange them. By doing so, you can drown the animal within. I use a pencil to make a light mark on the very top of the egg. This mark must always stay at the top.
Because Leopards are one of those animals which are temperature dependent for sex development, the temp you incubate at will determine the sex of your offspring. Around 80 to 88 is considered optimal. 80-82 will be females, 87-88 will be males, and in between you will get roughly half and half. Most folks I know go for more females, incubating at around 81.
I don't understand the part about incubating the incubator to a temperature.
If you could clarify that question, I'd be glad to answer.
There are many different designs for home-made incubators out there ...from the simple to the frighteningly elaborate. You can also purchase a purpose built incubator. If you do a cursory web search on "
leopard gecko incubate eggs", you'll get quite a few examples of what people are using.
Bob