I don't use an incubator at all to hatch my eggs.
They simply go into an sterilized (using F10) plastic takeaway tub that's sealed to make it airtight.
It sits on the coffee table ( never colder than 23 degrees C in our home ) until they start hatching at which time I either add a sliver of chow or a small fresh mulberry leaf.
The trick is to keep the rearing conditions in the sealed tub
> dry
> clean
> and to keep micro-predators such as house ants, small spiders, small wasps out.
If the food starts to show any white or yellow fluffy mold you need to remove the moldy stuff immediately as it's lethal to the worms.
Commercially available eggs have usually been keep in a chiller , so should start hatching inside a 1 to 3 weeks.
I keep my surplus eggs in zip lock bags (on the paper they were laid onto) in the door of the refrigerator (for up to 2 years) . If the cool place for keeping the egg dormant is colder than 7 degC it will kill the eggs. Once the eggs have been warmed up , you have to let them hatch as rechilling them seems to kill them.