Keep in mind, each Kumon is a franchise, so the interviewing process may differ from center to center. I found the job posting on my university's career site, and submitted my resume and cover letter. Less than two days later, I got an e-mail asking for an interview. The interview was held less than a week later. Pretty typical questions, like "How are you under stressful situations" and "What do you know about Kumon?" After the questions, I was asked to provide my resume and my grades (both high school and university) - make sure you bring print outs! All in all, the interview was 10 min or less. I received an e-mail about a week later offering me the job. A police check is required since you will be working with children (in Canada, at least).
I have been working at Kumon for over a year now. All of the assistants are either high school or university students. I did not have previous job experience before this - just volunteer experience and very high grades.