Adcoms will probably never say this out loud, but it's a big negative to apply to b-school while unemployed (even if you are doing something like language school, traveling, etc). If b-school is your priority, do so while you're still working or at least taking on some sort of volunteer activity at an organization that has the kind of responsibility equivalent to a full-time job.

Also, to be blunt, you are NOT going to really master a language in 8 months. Especially Mandarin, even if you have some background in it (are you Indonesian Chinese?).

Being fluent in a language requires consistent use and exposure. If you're there for 8 months, and then come to the US for school -- you will lose a lot of the progress you made when you're in an English speaking environment.

Being fluent (or near fluent) in Mandarin can be incredibly helpful or even necessary if you're going to be working in China or have a lot of interaction with Chinese vendors/customers/investors/etc but the thing is -- it's not just spoken Mandarin, but also learning how to at least read Chinese (which will take a few years to get to a point where you can read business correspondence - basically you need to learn around 1,000 characters to get by with everyday stuff like road signs, menus, basic text, Facebook status updates, etc. and 1,500 characters for functional literacy, and ideally close to 2,000 characters to read a newspaper and/or business correspondence comfortably). And how you learn to read Chinese characters comes down to rote memorization (trust me, I know from experience!).

I'm not trying to discourage you from learning Mandarin. It's that if you really want to learn it to a level that matters in business, you need more than just 8 months (and then not using it 24/7 when you're in the US). It takes a few years, even if you are not a beginner but already have some functional conversational Mandarin already under your belt. Which is why you shouldn't just quit your job.