Keep your job and start selling the product. Don't take investment capital unless you absolutely have to, and don't quit your job until your profits are high enough that you can do so comfortably. If you do it this way, you'll relieve some financial uncertainty as well as put yourself in a better position to negotiate should you raise money in the future (you end up saying "We have a profitable business" instead of "We have this thing we haven't sold to anyone yet").