[jeffreportmill1]

If you have like-minded buddies, you are way ahead of the game (even if you don't have an idea). Choose something that seems fun - maybe something you would want to buy/use yourselves and start working on it. Borrow 8 hours a week from your current employer. They won't miss it, because you will probably gain that much in productivity as your skills and morale improve.

In the end, if you find success (which is rare) it probably won't be with your original idea. Once you have a body of work, keep an eye out for other applications of your core technologies. When your real idea comes along, be willing to pivot.