Back in 2011 myself and a few mates built our startup over 1 year. Mainly on weekends and sometimes after work, it was a long hard slog - but it ultimately got is into a startup accelerator.. which for me back then was one of my big goals.

We all quit our jobs when we got into the accelerator. I was young, and felt that had to be the way. In retrospect one (or two) of us could have continued working part time even at that point. The company slowly fizzled out over the following year. We failed to secure adequate funding, individually ran out of runway, with a splash of co-founder misalignment.

In retrospect we could have done a lot less, and figured all of it out sooner. Not sure if that was a helpful answer :)