It's an interesting question and not one I've considered before. I guess I felt I had joined the hobby when BJDs became something I kept returning to again and again, something that made me happy, held my interest, and occupied my time...the same as my other hobbies. For me, this was before I bought my first doll. It was the stage where I was researching sculpts, watching tons of box openings & tutorials, building comparison spreadsheets, and making my first doll plans. When I bought my first doll, I didn't feel like I had finally joined the hobby. I just felt like I could then experience different aspects of it, the aspects related to owning and handling the doll.