Perhaps none. I guess that they may have taught errors all the way back then ... since they didn't define doctrines.
Poor lad, you're all confused. Let's hope this helps clear up your confusion.
The Apostles were each personally infallible after the descent of the Holy Ghost upon them at Pentecost, so whatever they taught, whether alone, in assembly, or dispersed throughout the world, really was infallible, so you see, they actually would have had no need to assemble for the same reasons Councils have assembled since.
Meanwhile, the NO agrees that the Apostles were personally infallible, but to that, the NO have added "collegial infallibility", which, while (I presume) you KNOW the NO collegiality crap is error, yet you believe collegial infallibility to be a de fide doctrine of the Church.
The NO created the condition of the bishops' infallibility being dependent upon their collegiality, aka unanimously teaching the same thing while being in union with the pope, this is the way it works since the "New Pentecost" of V2. Sometimes, people forget the part about being in union with the pope - but Cantarella was right on top of it!
We had our Pentecost and the NO had theirs, you're trying to get the two to agree, but by design, that is a doomed proposition and only adds to your confusion.
Hope this clears up some of your confusion.