After Paul was selected, he began to work in a few years, almost immediately.
On Paul's way to Damascus, the light of the Lord shone on him all around, so that his eyes could not see; The Lord sent Ananias to pray for Paul, opened his eyes and was baptized for him (Acts 9: 3-19); Saul stayed with the disciples of Damascus for some time, and then he preached Jesus in the synagogues, claiming to be the son of God (Acts 9: 19-20).
Hallelujah!