Certainly by the second century there was a method to know what the universal truth ought to be** (at the very least, whether it was actualized or not). Irenaeus says:
[INDENT] “It is possible, then, for everyone in every church, who may wish to ** know the truth**, to contemplate the tradition of the apostles which has been made known to us throughout the whole world. And we are in a position to enumerate those who were instituted ***bishops by the apostles and their successors ***down to our own times, men who neither knew nor taught anything like what these heretics rave about” (*Against Heresies *3:3:1)
“But since it would be too long to enumerate in such a volume as this the successions of all the churches, we shall confound all those who, in whatever manner, whether through self-satisfaction or vainglory, or through blindness and wicked opinion, assemble other than where it is proper, by pointing out here the successions of the bishops of the greatest and most ancient church known to all, founded and organized at Rome by the two most glorious apostles, Peter and Paul—that church which has the tradition and the faith with which comes down to us after having been announced to men by the apostles. For with this Church, because of its superior origin, all churches must agree, that is, all the faithful in the whole world. And it is in her that the faithful everywhere have maintained the apostolic tradition” (Against Heresies 3:3:2).
And early than him, we have Ignatius of Antioch speaking of bishops being established everywhere. His letters emphasize the necessity of being in union with the bishop.
As a note in relation to the concept of apostolic succession, the three primary sees – Rome, Alexandria, and Antioch – are all related to the Apostle Peter.