As I did on the last thread (and shall continue to do until some of it sinks in), I will point out that this is a false premise. Sola Scriptura does not, REPEAT, DOES NOT believe that the Christian faith should be based exclusively on a book. ONLY PRIMARILY ON THE BOOK.
If the books of the New Testament are "self-authenticating" through the ministry of the Holy Spirit to each individual then why was there confusion in the early Church over which books were inspired, with some books being rejected by the majority?
To which I will answer "Why did the Fathers get it wrong?" If Irenaeus and Jerome are so authoritative, why didn't they get it right for us? If the RCC existed from the beginning, why did they have a hard time establishing a Canon? Surely their hierarchy was fully developed and they could have dealt easily with such a problem.
What did the fathers get wrong? The Church councils did get it right if you accept the NT canon as I know you do. There were a number of false gospels and letters in circulation at that time that were causing confusion. The Church decided to eliminate the confusion by settling the canon. And since this was a council, you could expect discussion and debate. As I have posted before, II Peter was one of the books that made it in that was hotly debated. The book of Revelation was another example of this. And on a side note, I have always wondered how the letter to Philemon made it.