Awesome story. I graduated with a JD/MPA in 2010, but already started working in a startup the summer prior to graduation. I've been in startups ever since and have recently started to (slowly) teach myself to code. I haven't had the time or guts to volunteer to actually build something for someone, but I've been thinking that I'd like to get involved in an open source project in a couple of months when I'm more comfortable in the code.

When/how did you know that you would actually be able to build something useful?

Edit: P.S. Good move getting out of law! ;-)