In a well-researched and comprehensive blog series on the Christian canon, Dr Michael J Kruger addresses the dating of the Christian canon.
It is a common misconception that the Christian canon is late, sometimes people even date it to the earliest text listing the exact books which are now included. This is misconceived; the point should then be Athanasius’s Easter letter from 367 AD. But it is as if my wife’s family came into existence the moment she describes their pedigree, their family relationships et cetera. She is listing them in 2012, but some of the relatives go back to the 17th century!
The canon came about as one of three intertwined factors: sound doctrine, canon, and succession of ministers. And very early (I believe, against very many of my colleagues, I admit), perhaps as early as the 60s, Paul’s letters could be described as graphē, Scripture (2 Pet 3:15–16). The gospels emerged from their inception as ‘oral texts’ transmitted from disciple to disciple until they were committed to writing and gathered into the gospels. A process over 30+ years, and perhaps it is from the 60’s that the earliest gospels can be dated.
This teaches us a lesson: within the first generations of eyewitnesses the core of the canon was formed, and there were people around who could guarantee that e.g., the authors really were authentic.
Another lesson is that one cannot put church early and Bible late. Some people like to use the idea of the list from 367 to say that in the beginning was the church and really no Bible. In the beginning were both, so intertwined that you cannot separate them.
And one more: Bible, doctrine and apostolicity are always intertwined. Then and now.