Few had a new testament. :)
That is true.
But by the end of the first century A.D., they had a group of writings that made up what we know today as the New Testament. They were LIVING the creation of the New Testament and their local congregations received the writings from the Apostles and disciples as they were written, copied and distributed throughout the region and then the world.
A good exposition of this is The Formation of the Canon of the New Testament.