Since you’ve given enough details to identify yourself, I would go ahead and pull the trigger on the Facebook offer as promptly as possible.
After you leave your current job, people will look at your empty chair for several weeks and shrug. After 3 weeks, there will be someone new sitting there. After 6 weeks, you won’t be mentioned. After 6 months you won’t be remembered. After 6 years, you won’t remember them either.
Just to add on to this advice: if you want to do an MBA (or really even if not), stay at Facebook for a few years. Otherwise, people will think you either can't hold down a job or just lack commitment. That's a bad image to have whether you're applying to graduate programs or starting a career.
I can tell you as someone in business school now, my resume has some similarities and it has definitely hurt me.
After you leave your current job, people will look at your empty chair for several weeks and shrug. After 3 weeks, there will be someone new sitting there. After 6 weeks, you won’t be mentioned. After 6 months you won’t be remembered. After 6 years, you won’t remember them either.