I believe this present age of grace began with Saul’s conversion (which was totally off the prophetic script) in Acts 9 (1 Tim. 1:12-16). Acts 13 also has great dispensational significance. The number thirteen in the Bible is the number for separation (unto good or bad, see chapter 13 in Genesis through Deuteronomy). Paul has a ministry that is separate from the twelve apostles. We could call him the thirteenth apostle. His ministry to the Gentiles was not based on the rise of Israel, but on their fall (Rom. 11:11-15). He wrote thirteen epistles by inspiration of God to the Body of Christ. God did not send Paul out of the Jewish church in Jerusalem, but out of the Gentile church in Antioch. God waited until he and Barnabas returned from Jerusalem before He sent them out on their first missionary journey (Acts 12:25). The apostle James was killed in Acts 12, but he was not replaced like Judas was in Acts 1 (in preparation to offer the kingdom to Israel, Matt. 19:28). The apostle Peter went off the scene, for the most part, in Acts 12.
In Acts 13:
1. Paul was separated unto his special ministry among the Gentiles, and was sent out of a Gentile church.
2. Paul pronounced temporary blindness on an apostate Jew that tried to keep a Gentile from hearing the word of God, and as a result of that blindness the Gentile believed. This was the first recorded miracle of Paul and provides a dispensational picture of this present age (Rom. 11:25).
3. Saul will be known by the Gentile name of Paul from v.9 on.
4. Note v.13 - It had been "Barnabas and Saul." Saul was mentioned last among the prophets and teachers in Antioch (v.1). From this point on, it will be "Paul and his company." I think this had something to do with the departure of John Mark in 13:13. Mark, who was related to Barnabas (Col. 4:10), was from the church in Jerusalem and had a hard time with the Gentile ministry of Paul. He later recognized Paul's authority and became profitable to him for the ministry (2 Tim. 4:11).
5. The first recorded message of justification by faith without works was preached by Paul (v.39) to the Jews and any that feared God from among the Gentiles (v.26).
6. Paul gave an important warning to the Jews, and made an important declaration concerning his ministry (vs.40-47).
7. Paul made his first of three pronouncements that he was turning from the Jews to preach to Gentiles (v.46).
8. Many Gentiles were saved in the city, outside of the synagogue and apart from the Jews (vs.48-49).
9. The disciples were filled with the Holy Ghost (v.52) for the first time without any reference to water baptism or the laying on of hands.
10. The key verses in Acts 13 are multiples of 13 (v.13, 26, 39, 52).