Time management is the sixth reason to keep your day job. You've disciplined yourself to get up an hour early and write. Or you block two hours after dinner to devote to your writing career. Maybe you use all of Saturday afternoon to knock a rough draft of a chapter. Why? Because you know that a good portion of your working day is spent at the day job. You fit the writing into your schedule.
But when you quit your day job, there's no longer a schedule. You have all day to write. Yet, many times other things get in the way. Like watching a morning talk show, reading the newspaper, chatting with your neighbor.
Ask yourself if you are disciplined enough to get into a "home office" routine. Getting up and getting your day started just as if you were commuting and reporting to your day job. I'll be the first to admit that if I didn't have to get up at 6:30AM during the week, I wouldn't so that means my morning routine would be pushed back into at least mid-morning. Which translates into less than an eight hour workday for me. Sounds wonderful but not realistic if I was trying to live off my writing income!