As somebody who quit a job to pursue a startup, I'm going to take the opposite side.
Don't quit your job to pursue a startup unless:
1) You have a customer base lined up and some income is all but assured, or...
2) You have enough savings to get by for at least one year (including insurance) and a skill set or network that would enable you to jump back into a similarly desirable job right away.
Quitting with just an idea and strong cofounders is a recipe for disaster, stress, and misery. Remember, building is fun and easy, making sales isn't.
First whittle down what you really need to start (often times it's a lot less than you originally thought) and examine whether you really have to quit. If you are building something that your employer could lay claim to due to your employment agreement, it's a little more tricky, but if you are careful it is pretty easy to get around that.
There is also the option of part-time consulting to pay the bills while building the startup. As a Django consultant, this person could probably make $50k annual income by consulting a few days per week. The rest of his time could be dedicated to the startup business.
Even if you have low living costs, you should still consider opportunity costs of not working. A consultant making $100k per year who takes two years off to do a failed startup has effectively lost $200k in income.
One recommendation, stolen from patio11: sell weekly blocks of your time. This is more fair to both those hiring you, and to your startup, because ramp-up and context-switch time are an expensive part of software development.
This is what I've started doing. Right now I'm consulting for a TechStars company doing some Akka stuff while I work on my own venture.
I'm single and 22 so doing this for a few months brings in enough to float me for ~year, not including the savings I had from the BigCo job I recently left.
The real bonus, IMO, comes from the fact that your former consulting clients are your most likely bet for job prospects if/when your venture fails, assuming they like your work of course.
2) Actually scares me. Without a fire under my feet I fear I might get too "comfy", not ship because of perfectionism, and not focus on the most important things (I'd work on coding instead of customer development and sales).
See if there's some way you can organize with your bank or a friend to limit your access to your savings, being only available in the event that everything falls apart and you have to go back to regular life.
This way, you won't feel like you have too large a safety net.
I agree with all of the above, except I'd recommend having enough for 1.5 years. You're going to spend the first few months doing setup work for the business.
Although I generally agree with your point, I've found that the difference between working on a project full time and working part time is a night and day shift. There's a lot more pressure to make those sales if you define your full time job is making your business a success. I've done both, and found the full time option to be more likely to produce success for me.
The other thing was that I got lucky on my first startup and have a bit of income coming in from that, which means the cost of failure is pretty small. As an econ major in college, I'm well aware of the opportunity cost of not working, though, which did weigh heavily on my decision.
Don't quit your job to pursue a startup unless:
1) You have a customer base lined up and some income is all but assured, or...
2) You have enough savings to get by for at least one year (including insurance) and a skill set or network that would enable you to jump back into a similarly desirable job right away.
Quitting with just an idea and strong cofounders is a recipe for disaster, stress, and misery. Remember, building is fun and easy, making sales isn't.
First whittle down what you really need to start (often times it's a lot less than you originally thought) and examine whether you really have to quit. If you are building something that your employer could lay claim to due to your employment agreement, it's a little more tricky, but if you are careful it is pretty easy to get around that.