How did you start?
Basically just start. Without money there doesn't need to be a grand scheme of how things will work. You'll figure out things as you go based on what will work for your community.
How long were the planning stages?
Virtually nonexistent. Basically I tried to figure out if there was a free school in Seattle already, met with someone and got going. Creating a poor but functional website and setting up an email address were the first steps. Once that was done "spamming" friends, neighbors and coworkers and anyone else on my email list was next. From there I scheduled the first class (you'll probably need to step up and teach a number of classes to get the thing rolling... people are much more confident about teaching if they aren't teaching the very first class... but who knows you might find someone that is ready for that in your community) and sent out press releases. These releases were poorly written by me and certainly not professional. Basically I went around finding free papers, picking up a copy and including email addresses from these folks into a "press" group. Pretty simple really.
Other then that things happened as they happened. With no money to raise, no board to answer to and no metrics required to prove our success things happen when they do. Do things in a way that makes logical sense to you. For me, being a computer worker in a town of computer users the website and email was most important. It could be that having classes is the way to start depending on the size and needs of your community. Eventually people will want someplace to look to find out more and thus a website is a good thing to have early on.
And, how did you gain community support?
Social networking basically. I emailed my friends and begged them to pass it along. We use facebook and other tools to spread the word. Newspapers picked up on it and we got a ton of press early on (most likely because we don't operate with any donations). We hung flyers around and that helped spread the word. We also looked at other places to post, like craigslist, etc and pushed out the word there. Basically things grew organically and at a steady pace. The only time we had a serious jump in involvement was when we made the front page of the local section of the Sunday Seattle Times. Our enrollment in our email list bumped up over 100 people in less then 24 hours thanks to that press.