You have mis-representated the availability of copies of the New Testament in the early church. Qumran fell to the Romans in 68 AD. It was not a part of the Christian community, and yet fragments of the LXX and various books of the New Testament were discovered there. Some of these fragments were in a script known as Zierstil, which was used in Egypt between 100 BC and 50 AD. Other NT fragments were in the Herculann script, used by the scribes from 50 AD to 80. The point being that these copies prove the New Testament was in wide circulation before 68 AD.
How many people were alive per complete set of “Biblical Scripture” in the time and region you mention? That number is probably well over 100,000 even if you can prove that a complete set of Scripture existed there, prior to AD 400.
What was the literacy rate? I have posted estimates in the region ranging from 1.5% to 20%.
Most early Christians NEVER read the “Bible” or any authentic written portion of today's accepted Bible versus.
IT WAS SPOKEN TO THEM!