There's no harm in starting the demo trading now. Just know that there will be a lot of failure before you get the hang of it. PipSchool is really just giving you a basic understanding of what Forex is, and it is great - don't get me wrong (I think just about everyone starts at babypips), but applying that information is a whole other beast.
If you get your demo account up and going, you're more likely to start becoming more active in the forums and figuring some things out like your trading style, plan, rules, money management, etc. So whenever you feel ready, jump in. It's just demo. Good luck. And don't put real money in it until you're consistently profitable over a period of time.