Ask the medical school admissions office if you're allowed to apply for a job while in medical school. Certain medical schools prohibit students from applying for jobs while in school unless special circumstances apply, such as the need to financially support a child.
Work through medical school for two to four months. During that time you'll experience how difficult medical school is and determine whether or not you'll have time to get a job. Some students find that while medical school is difficult, holding down a job is possible, while other students would not be able to do justice to both their jobs and their studies.
Apply for part-time jobs and speak to the manager when you submit your application. Tell him that you are a medical school student and you're always busy, but you would like to work a certain number of hours each week. Try to work no more than 20.