The day Stephen was stoned, Christians began fleeing Jerusalem. Whether diaspora pilgrims who never went home or Judean believers who hated to leave, they all had two things in common. They were suddenly homeless, and they had no one but each other to rely on.
Given those facts, Acts 8 does not have to tell us the details of the scattering. Generally, what must have happened is that little bands of Jewish Christians regathered together in as many places as they were able to find one another. Whether just passing through or whether looking to stay, little bodies of Christ were set up, again and again, all over Palestine.
As any church is one corporate Home for the Lord, one dwelling place assembled from many parts, so it was that God put together in these days a series of Tents for Himself, each temporary to some degree or another. As these mini churches continued to sprout, all over Israel, God's House and His Testimony was once again moving across the face of the Earth, for the first time since David took Jerusalem.
These are the obvious after-effects of Acts 7. Combined with an assumption of historicity for the basic content of Stephen's speech, and given the chronological data that Paul's conversion took place less than twelve months after Pentecost Sunday - which narrows the most likely timeframe for these events to some time during the Autumn of 33 AD - one should find it remarkable to consider the following thoughts.
Reconstructing this picture of autumn events, the aftermath of this scattering suddenly looks a lot like God's 'ingathering'. The small churches being assembled now seem a spiritual version of the Sukkot (Shelters/Booths) that went up during Israel's autumn festival. The original church - driven away from Jerusalem to appease the guilty consciences of the Sanhedrin and their closest adherents - amazingly, the Jerusalem church now parallels the scapegoat, sent out into the wilderness, to wander the face of the earth.
This much, at least, we ought to conclude: That WHATEVER day Stephen was stoned, these events happened afterward. And that, whether or not this suggests Yom Kippur as a likely historical context for the events of Acts 7, these parallels are remarkably like a fulfillment of much in the High Holy season.
Jesus may not have been crucified at precisely the time that the Passover lambs were being slain in the Temple. Nevertheless, Jesus' death WAS very much a fulfillment of Passover in Eternal ways.
Likewise, Stephen may not have been stoned on the Day of Atonement, but these events which occurred after Stephen's death DID mark a first-time fulfillment of Tabernacles in Eternal ways.
A first-time fulfillment, at least...