Took about a week. I went in for a laid back interview at the main building in Boston, where I met with the volunteer coordinator. She was very friendly, which made the interview go smoothly. I got called back for another interview in the Quincy facility, and sat down with staff to hear more about what I would be doing as a volunteer. The second interview was more like a getting to know you introduction, and I was pretty much guaranteed to become a volunteer at that point.