I doubt there was a chairman at Pentecost 33 CE. But I bet their was a chairman for this one.
AM, you would be surprised there were actually two. the texts read that the 'first voice' switched between Peter and someone else (dont remember the details) it was used by wt inc to introduce the rotating elder arrangement in the early 1970ies.
A surprising arrangement with many benefits for the congregations. The narcissists hated it. soon it was back to the "gifts of god to men" bullies at the top. after 1975, downhill it went.