Did Paul have the complete revelation of the Gospel of Grace?
No, Paul did not have the complete revelation of the Gospel of Grace. Even with all his revelations, he still did not have them all. There would be more coming, and he knew only in part. He preached partially, lacking the whole revelation at that time.
Les teaches that Paul himself understood there was not a full knowledge revealed yet. Even with all of his revelations, Paul still did not have them all; more was coming. Paul says, "We know in part, and we prophesy in part." He still did not have the whole revelation of the truth of the Gospel of Grace. This was only the beginning.
1 Corinthians 13:9
For we know in part, and we prophesy in part.
1 Corinthians 13:10
But when that which is perfect is come, then that which is in part shall be done away.