That's just an estimated date. The egg could hatch earlier or even a couple of months later. Just make sure that you have your cage set up and ready to go. And make sure that you are actively culturing fruit flies.
The baby cham will be fine in the container until you get back from school given that the egg has proper humidity and no way for the little guy/gal to escape. Hatching can take a lengthy amount of time, even if the head pops out. Whether you want to skip school that day is up to you.
Taking care of a hatchling is considerably harder than taking care of a 3-month-old cham. Now is the time to get everything dialed in. With that said, I doubt the egg will hatch exactly on the estimated day. Don't get discouraged if it doesn't hatch then. The egg is still good.
Here's a podcast link about egg hatching:
https://chameleonacademy.com/hatching-a-panther-chameleon-egg/
Also, if you want to send us pictures of your enclosure while also noting the supplements you are planning to use and the hydration (misting/fogging) setup, we can give you feedback and advice.