Saul returned to Jerusalem after three years in "Arabia, and a return to Damascus".  In my play, ALL THINGS TO ALL MEN, I say it is, because  he wants acceptance by the other apostles. In Acts it says he "attempted to join them".

The meeting in the beginning didn't go well, because the apostles were afraid of him, but Barnabas (the other man who was separated by God to spread the gospel), interceded on his behalf and reminded them of how Saul was converted by the "miracle" on the road to Damascus.

In Galatians he says that he was with Peter and he saw James, the brother of Jesus. He also states that these were the only apostles that he saw. 

Now, in Acts we read that prior to this meeting, James the brother of John, the sons of "Thunder" was executed by Herod, king of Jerusalem.  James must have been the most outspoken of the followers of Jesus to be singled out. So, being a follower of Jesus during the reign of Herod was a time of danger for them.

Herod was not a "Jew" by birth. He was Idumean, and they were conquered by John Hyrcanus, a Macabean Jew who compelled the Idumeans to be circumcised and adopt  Judaism. Herod was always trying to prove his "jewishness" to the Jewish leaders in Jerusalem. He saw that killing James pleased them and later he imprisoned Peter. 

I mention this to "set the stage" for the initial meeting between  Saul and  the Apostles James and Peter. They must have met in secret, because Saul's changing "sides" must have made him a marked man to the leaders of the Jews. This probably  was why the other apostles weren't present.

Again he returns to Jerusalem after fourteen years, having received a revelation to do so, and presents the gospel that he teaches to the Gentiles to James, John and Peter. At this time, Herod was no longer King of Jerusalem.

They accepted  what Saul was preaching, that excluded circumcision and the other Judaic laws, realizing  that his was a "different" gospel for the Gentiles  and he was only asked not to eat food that had been put before idols.

I doubt that he brought out what was to occur in the "celestials" at this time.

So, a definite demarcation  was set between those apostles who are with Peter and those who follow Paul.

"Rob Peter to pay Paul"..paulnbob