I'm curious - where did you get the two year time frame you mentioned there?
Thanks,
Romans 5:8.
Just read Acts 1-11 and you will see that the events happen very quickly.
Acts 1 & 2 are all over by Pentecost after the Passover when Jesus died and resurrected. At Pentecost the number of Christians increased by over 3000.
We read:
Acts 2
7Utterly amazed, they asked: “Aren’t all these who are speaking Galileans? 8Then how is it that each of us hears them in our native language? 9Parthians, Medes and Elamites; residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia,b 10Phrygia and Pamphylia, Egypt and the parts of Libya near Cyrene; visitors from Rome 11(both Jews and converts to Judaism); Cretans and Arabs—we hear them declaring the wonders of God in our own tongues!” 12 Amazed and perplexed, they asked one another, “What does this mean?”
Acts 2:41
Those who accepted his message were baptised and about three thousand were added to their number that day.
Then we see in Acts 6 verses that read like it was soon after Pentecost, note the countries and wonders performed and Pentecost was attended over one week:
Acts 6
8Now Stephen, a man full of God’s grace and power, performed great wonders and signs among the people. 9Opposition arose, however, from members of the Synagogue of the Freedmen (as it was called)—Jews of Cyrene and Alexandria as well as the provinces of Cilicia and Asia—who began to argue with Stephen. 10But they could not stand up against the wisdom the Spirit gave him as he spoke.
Paul was at Stephens stoning and then the church was scattered:
Acts 8:1
And Saul approved of their killing him. On that day a great persecution broke out against the church in Jerusalem, and all except the apostles were scattered throughout Judea and Samaria.
Saul goes to Damascus to capture them by Act 9 which is after this event soon after Pentecost. Then by Acts 11 notice how it mentions the scattering
Acts 11
19Now those who had been scattered by the persecution that broke out when Stephen was killed traveled as far as Phoenicia, Cyprus and Antioch, spreading the word only among Jews. 20Some of them, however, men from Cyprus and Cyrene, went to Antioch and began to speak to Greeks also, telling them the good news about the Lord Jesus. 21The Lord’s hand was with them, and a great number of people believed and turned to the Lord.
22News of this reached the church in Jerusalem, and they sent Barnabas to Antioch. 23When he arrived and saw what the grace of God had done, he was glad and encouraged them all to remain true to the Lord with all their hearts. 24He was a good man, full of the Holy Spirit and faith, and a great number of people were brought to the Lord.
25Then Barnabas went to Tarsus to look for Saul, 26and when he found him, he brought him to Antioch. So for a whole year Barnabas and Saul met with the church and taught great numbers of people. The disciples were called Christians first at Antioch.
The mention of a year in the above verse is the first mention in Acts of a period of time greater than a day!
So the term Christian came about from about the summer after Christs death to the following summer.