It has been pointed out that in early Christianity, in cities with large populations, all the Christians might not have been able to meet in one place to worship, and thus there might be numerous congregations (or house churches). If this is so, and supposing that the office of bishop was in place, would there have been a bishop for each of these house churches, or just the city at large? Was their uniformity in such matters by, say, the time of Justin Martyr (mid-2nd century)? When did things begin to take on a uniform character as far as bishops and their jurisdiction goes?
It would seem from St. Ignatius' letters (and he is writing from and too what must have been among the largest Christian populations at the time) that there was one bishop for each city. It so remained in Alexandria herself for centuries for all of Egypt. The bishops, on the model of the synagogue, had a council of presbyters with him, out of which came the presbyters (i.e. priests) that ministered in the bishops absence (St. Ignatius speaks of "the bishop, or one designated by him"). There were presbyters who were not ordained, and we assume functioned as the elders of the synagogue (i.e. no priestly function), and the chorbishops, who were bishops in the countryside attached to the city who were bishops but functioned like priests. (the chorbishops come from before presbyter was clearly seperated from the episcopate, and is a vestige of the office of presbyter under the Apostles. See Acts 20:17, 28. That is the reason why St. Paul doesn't enumerate the qualifications of priest in Timothy).
Since the question of jurisdiction was an issue in Hebrew, Jewish and Greco-Roman society, and in all cases was a hierarchy based on the city/polis, it would follow that the Early Church would go with what it knew, which is what all the available evidence indicates. Note: St. Paul tells St. Titus to ordain presbyter-bishops in every city
Titus 1:5,7. That part was uniform from the beginning.