Sola Scriptura the way of the Apostle's? huh

While reading one of the blogs of a very influential man in the Southern Baptist world he ended his entry with the statement that Sola Scriptura was and has been the way of the true Church of God.

Without bringing up past arguments about the need for tradition, how Paul (a reformers best friend) categorized both oral and written teachings as tradition, or when Paul wrote to Timothy about how the scriptures become your complete go to guide the only thing he could have been talking about was the Old Testament due to the fact that half of the New Testament had yet to be written at the time...

The point I want to bring out has nothing to do with theology or the Early Church Fathers, but rather with common sense. It wouldn't be until the Councils of Carthage and Hippo in the LATE 300's that the Church would have a formalized canon. Before then local congregations used what hand written copies of epistles and gospels that they hand (mind you the printing press was far from being invented) and even then locating complete copies of Gospels and Epistles was costly.

Thus, if there was no formal, universally agreed upon scriptura until the late 300's how could sola scriptura have been the way of the Apostles much less the Church for nearly 400 years?