I was in a similar situation and my STRONG advice is to kill it working nights and weekends on your project before you quit. You need tons of inertia...3 things you should have before you quit:

1. some demo/prototypes done 2. a 15 slide business plan 3. one other person that will dedicate him/herself on the level that you are planning.

You will have a newfound appreciation for stability if you do your own company no matter what the economy looks like.