When does the Bible say the Gospel was first preached? I used to answer, the Day of Pentecost, as recorded in Acts 2, until I read this passage,

And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel to Abraham beforehand, saying, “In you all the nations shall be blessed.” So then those who are of faith are blessed with believing Abraham (Gal 3.8–9).

God Himself preached the Gospel to Abraham, as found in Genesis 12.3, that in Abraham all the nations of the Earth would be blessed.

Therefore, whether you are a Jew or one of the other nations of the Earth, you can have faith and be blessed with the great man Abraham!