Man, I feel silly now. I have several times more than $15K saved up. At grad-school living expenses, perhaps 3 years of runway.

I'm not really sticking with the day job for financial reasons though. I want to see the product I've been working on ship. Get it into the hands of actual paying customers. Because I figure then I'll get to see a whole bunch of other problems that will likely impact the startup too. Much better to make the initial mistakes on someone else's dime.

Problem is, my day job seems to move at a glacial pace. So despite having a 6 month handicap and about 1/5 the number of man-hours available, my startup may launch first. If that happens, I'll probably quit the day job whether it's done or not, because it's just a drag on the startup.

That's still plenty respectable. Woz designed most of the Apple II in his apartment while working at Hewlett Packard. However, (if my memory serves me correctly) he left HP to put the finishing touches on the design before it launched.

So perhaps it might be best to leave when your product is about 80% to the point of launching, because then you can focus full time on actually getting it out the door, and on the aftermath. If you have a day job, it might never seem like it's ready to launch.

But that's just my hypothesis; I don't have any actual experience with that. :)