What names does Paul give to the Gospel he preached?

The names are "My Gospel," "the Gospel of the Grace of God," "that Gospel which I preach amongst the Gentiles," and "the Gospel of the preaching of Jesus Christ according to the revelation of the secret," which had been kept secret from ages past.

Les explains that the Apostle Paul brought the gospel out to the Gentile world, and now God lays responsibility upon Gentiles to believe the gospel. Paul calls it "My Gospel," the "Gospel of the Grace of God," "that Gospel which I preach amongst the Gentiles," and the "Gospel of the preaching of Jesus Christ according to the revelation of the secret," kept secret from ages past. Les emphasizes that this is what we are to believe today: that which God has revealed to us.

Romans 16:25

Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began,

Romans 2:16

In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.

Acts 20:24

But none of these things move me, neither count I my life dear unto myself, so that I might finish my course with joy, and the ministry, which I have received of the Lord Jesus, to testify the gospel of the grace of God.

When was the mystery of Paul's gospel revealed, and to whom?

The mystery of Paul's gospel was kept secret since the world began and was revealed when God made it known to Paul. According to Romans 16:25, this secret, comprising the whole circle of Paul's doctrines, was revealed to him, with deeper revelations later given in Ephesians and his prison epistles.