In #157 I wrote: “We understand then that the Church has always maintained the infallible teaching authority of the Supreme Pontiff, as expressed in Vatican I, and that it’s formal definiton only was made at Vatican I.”
Which I clarified to Mardukm: “… the formal dogmatic definiton as “infallibility” was finally made at Vatican I, and the limits were elaborated at Vatican I and II, yet the finality of the teaching authority was confirmed long ago as mentioned in the Vatican I statements.”
It is the finality of the teaching authority of the Supreme Pontiff which implies infallibility as defined at Vatican I.
As you asked, “first 1000 years (or more)”. It does include Hormisidas, 517 A.D., in the footnote given, and Constantinople 4 869 A.D. is listed, but Lyons 2, and Florence were after 1000. In general, however, Vatican I includes all statements of the councils as explained in earlier posts, including all before and after 1000 A.D.
You can read the relatio of Bishop Gasser from Vatican I, translated into English for insight into what they voted on.
The Gift of Infallibility: The Official Relatio on Infallibility of Bishop by James T. O’Connor.