We don't know how the original plan might have worked.
Ever read Acts 1-7?
It was working, at least initially.
My thought is that the original plan involved much larger numbers of Jews believing and being sent out,
This is literally the plot of the Bible.
Israel was always meant to be a spokes-nation to the world. God had spokesmen (prophets), and tried to scale up. Acts shows that it didn't work.
So God went to plan B, a mystery kept secret from the foundation of the world, using one person to go to all nations.
but because Paul and company were persecuting instead of joining the movement, God determined a new way
New way?
Try "mystery kept secret from the foundation of the world."
(one He had considered before, but wasn't needed until the Jews rejected their messiah and His offer of forgiveness, as Peter offered)
This is the plot twist of the Bible.
of taking the message to the Gentiles, but not a new message.
"You must be circumcised" and "you don't have to circumcise" are the same message?
Remember that the message was verbalized somewhat by the angels at Christ's birth.
Luke 2:14 KJV — Glory to God in the highest, and on earth peace, good will toward men.
Nowhere in the gospels is Christ's death burial and resurrection openly preached. And prior to Paul's conversion, Christ's crucifixion is preached as a condemnation against the Jews, not as the core tenet of salvation. (cf, Acts 1-7).
But that's the core claim of Paul's message and subsequently Christianity as a whole, that Christ was raised to bring life to the dead, not to the remission of sins (which is something only found in the Gospels, Acts 2, in Acts 10:43 in the context of Peter and Cornelius, and the epistle to the Hebrews).
