Mba studying

Im currently in my last year of college, and I've always planned on working a couple years and then doing an mba. But how do you study for the Gmat given IB work-hours? You don't have time to study. Do you quit and study for a few months before the test? Or do you talk with your superiors to give you some hours to study (this i believe isnt really an option, i dont think they're really flexible in the industry)

Thanks!