There are pros and cons to cutting eggs. The purpose of cutting the eggs is to prevent the case of a ball python not being able to get out on its own (egg tooth not strong enough, etc.). But, cutting eggs introduce the risk of bacteria, etc. etc.
A lot of people cut eggs simply for the purpose of knowing if they got a morph.
I cut the eggs because it was day 69 and I started to worry.
Most people here will advice to wait until the first snake pips then cut the rest.