Do radical unitarians and Herbert W. Armstrong advocates believe that Mary told everyone, or anyone, that her son Jesus was the Son of God?

It is believed by radical unitarians, Herbert W. Armstrong advocates and various others that Jesus was the Son of God by virtue of his birth by Mary. If that was true then presumably she would have told that story to perhaps many persons. Throughout the New Testament various persons relate that "Jesus is the Son of God" but I can find no scriptures that relate of Mary telling anyone about this, so I'm left wondering how these various individuals came to know Jesus as the Son of God.