I've been breeding for 6 or 7 years now. My recommendation is to not cut until the first one pips on its own. I know it is so hard to wait. There are variables beyond the temp and number of days. There is the size of the egg itself and the amount of material that has to develop. There is whether or not all of your gauging is accurate, and then there is just nature. Cutting eggs, in my opinion leaves you more vulnerable to complications versus being of benefit. The other thing is that cutting will not change the results of the genetics nor the time in which the snake will climb out of the egg. They typically leave the egg about 24 to 36 hours after they pip. If you cut 3 days early and do no harm, they will climb out of the egg in 3 days plus 24 to 36 hours after you cut. It just isn't worth the risk. Patience grasshopper. They will pip.