Where and when did the body of Christ actually begin according to Les?
The body of Christ began after Pentecost, not at Pentecost, because Pentecost was a Jewish holiday with a Jewish message. It began when the gospel went to Jew and Gentile, especially at Antioch in Acts 11, as Paul preached Christ's death, burial, and resurrection by faith alone, and believers were baptized by the Holy Spirit into that body.
Les teaches that the body of Christ came on the scene in the New Testament sometime after Pentecost, though he acknowledges many disagree. He is convinced it did not necessarily begin at Pentecost because Pentecost was strictly a Jewish holiday with a Jewish message. Instead, he places its beginning when the gospel began going out to Jew and Gentile, especially at the church at Antioch, where Acts 11 says believers were first called Christians. That was not the Jewish believers at Jerusalem in previous years, but Gentiles coming in by faith in the gospel of the grace of God. So Les feels the body of Christ began when Paul began to preach Christ's death, burial, and resurrection, by faith and faith alone, without the law. As men and women believed that message, the Holy Spirit baptized or placed them into the body of Christ.
And when he had found him, he brought him unto Antioch. And it came to pass, that a whole year they assembled themselves with the church, and taught much people. And the disciples were called Christians first in Antioch.