then, after that: what comes next in the order, often a later stage reached once time has passed
This is a small connecting word with one job: it puts things in order. It tells you that what follows came after what came before. It says nothing about how long the gap was, nothing about why one thing led to another, and nothing about the hour or the day.
Sometimes the order is an order of events. A manager questions one debtor and then turns to the next; Jesus waits where he is and then tells the disciples they are going back to Judea. Sometimes the order is not in time at all but in a list, as when Paul ranks what God has set in the church, or when James counts off the marks of wisdom from above, starting with pure and moving on to peaceable. The word is the same in both places; only the thing being put in order changes.
Because it fixes order but not distance, it can span years as easily as minutes. Paul builds the account of his early travels on it, writing "then after three years" and "then after fourteen years", and there the size of the gap comes from the numbers he supplies, never from the word itself. Where a writer wants the very next move in a scene already underway, he is as likely to reach for the near twin of this word (εἶτα); in one sentence of 1 Corinthians 15 Paul uses both, one after the other, with no change of sense. Where he wants to pin something to a particular moment instead, he uses the word for "at that time" (τότε).
Nuances
Which Jerusalem visit Galatians 2:1 describes, and therefore how much the chain of ἔπειτα clauses in Galatians 1:18, 1:21 and 2:1 can carry as a complete and sequential itinerary.
- majorityThe ἔπειτα series, reinforced by the oath of Galatians 1:20, gives a complete and ordered account of Paul's contacts with Jerusalem, and the visit of 2:1-10 is the conference of Acts 15.; Hans Dieter Betz, Galatians (Hermeneia), on Galatians 1:18-2:10; J. Louis Martyn, Galatians (Anchor Bible), on Galatians 2:1-10
- minorityThe visit of 2:1-10 is the famine-relief visit of Acts 11:30, so the letter was written before the Jerusalem conference, and the ἔπειτα series need not be read as excluding a visit Paul had no reason to mention.; F. F. Bruce, The Epistle to the Galatians (NIGTC), on Galatians 2:1-10; Richard N. Longenecker, Galatians (Word Biblical Commentary), on Galatians 2:1