Did Peter understand the Body of Christ made up of Jew and Gentile in his early preaching?
No. The context states that Peter knows nothing of the Body of Christ in his early preaching and has no concept of this composition of Jew and Gentile. He only makes reference to it later in his epistles, near the end of his life, after it had been revealed to Paul.
Les teaches that Paul was the Master Builder who laid the foundation, and his letters are intrinsic to our doctrine because he alone was given these revelations with regard to this Church made up of Jew and Gentile. Peter makes reference to it in his little epistles, way at the end of his life, but Peter knows nothing of this in his early preaching. He has no concept of the Body of Christ, this composition of Jew and Gentile. But this apostle Paul has had all of this revealed to him.