I tried quitting my job and it was the worst 18mths in my life. My advice would be it's alright to take the conservative route such as school or job until your business starts to generate some sort of income. Furthermore, it might be better to do b2b first then try b2c.
B2B is two orders of magnitude easier to turn in to a business, no luck involved there, it's just really hard work and staying power.
There is lots of 'advice' floating around and plenty of it is given by people that seem to ignore their own advice, and I think that's the biggest indicator that you shouldn't be following it. Have a look at the people that are building, slow but steady and that eat their own dogfood in terms of advice.
Not quitting your school or your job until you make enough money that you can salt away half a year to a years expenses is good practice, and cutting down on your expenses as much as you can is good practice too. It's usually easier to save a buck than to make one.
Whatever comes out of that 18 month stint, you are a much wiser person now, so think of it as a school too, only a different kind.
best of luck!
I don't know of pithy sayings, but something along the lines of "going through the proper channels" is deeply ingrained in a lot of people. Following that advice has meant I've passed up a lot of opportunities and allowed people to, however well meaning, say no to things I otherwise could have done. I'm somewhat of a believer in "It's better to ask forgiveness than permission," but like all advice, you really need to think through whether and how it applies to your situation.
One other note: "It might be better to do b2b first then try b2c." I've almost never seen people advise businesses try to tackle B2C, and I think it's just the allure of being a recognizable name that attracts people to that market.
Now you mentioned it, I never heard anybody give b2c advice. Implicitly, I get the sense they are saying b2c.