What is your thermostat set to? You don't want the top of your substrate to be 92F if your ball python can burrow in that substrate. Doing that would cause the bottom of the tank to get hot enough to burn your bp. You actually want the bottom of the tank that hot, on the inside. I'd move some substrate and shoot that with your heat gun. You'll probably have to set your thermostat up around 93 or 94 degrees in order to get the substrate up around 88-90 degrees.

Depending on how thick and how moist your substrate is, it make take an hour or two to get up to temp. I'd give it a good 5 or 6 hours before making any adjustments.