What constitutes a "beginning?"
Laura and I talked about the concept of extra-marital sex for two years before we got married and another year before our first swap. We were in line at a fast-serve pizza place when Laura complimented a lady on her earrings. The four of us sat together to eat. They were fun, attractive and good conversationalists. After dinner, bills paid, we were getting ready to leave, saying how much we'd enjoyed our meeting and "Hope we run into each other again."
Laura asked, "How do y'all feel about mate-sharing?" An hour later Laura was doing Rick in our bedroom and I was doing Jo on our couch.