My initial interview was with the branch sales manager. My second interview was with a regional manager, the branch manager, and a senior sales representative. The interview was very relaxed with easy or basic questions. Your goal is to make the regional manager feel comfortable with your personality and skill sets.
For the fist interview, I sat and waited 30 minutes before being called in. For the second, I waited 45 minutes. Keep in mind the sales team is "busy" and as a field assistant your job is to work around and support them.