Hey there—this is an easy question to answer. In a perfect world you will NOT have to quit your job in order to apply to schools. After all, elite MBA programs do not want you to be unemployed. They will worry that when you graduate, you will again be unemployed! And that is their biggest fear. So you should try to stay at your job if you can. Now, that being said, if you already have left your job, you will simply need to address this gap in employment in your Optional essay. These optional essays are very difficult to write of course—because on the one hand, you need to be confident and not make excuses! But on the other hand, you DO need to explain why you have been unemployed. But provided that you write a great optional essay, you should be just fine here. Good luck!