I would suggest getting some good books on corn snakes and start to do the research. You should also get a basic understanding of genetics before you start. Also, do you know what you'll do with 20 babies if they hatch. Not everyone wants to buy snakes and they can sometimes be hard to place in good homes. If you can't find homes for them, are you ready to house and feed that many extra snakes?
Lots of things to think about, but I'd start doing a lot of reading now and find out as much as you can before making any decisions.