While Ignatius of Antioch offers the earliest clear description of monarchial bishops (a single bishop over all house churches in a city) he is an advocate of monepiscopal structure rather than describing an accepted reality.To the bishops and house churches to which he writes, he offers strategies on how to pressure house churches who don't recognize the bishop into compliance.
Other contemporary Christian writers do not describe monarchial bishops, either continuing to equate them with the presbyters or speaking of episkopoi (bishops, plural) in a city.
"Plainly therefore we ought to regard the bishop as the Lord Himself" — Epistle of Ignatius to the Ephesians 6:1.
As the Church continued to expand, new churches in important cities gained their own bishop.
Churches in the regions outside an important city were served by Chorbishop, an official rank of bishops.
Not everything over there is fully functional yet, and the internal links still point to this blog, and will for the indefinite future.