I received the following comment:

Something to note:
In the book of Joel the Spirit outpouring (2:28-32) comes after the Great Ingathering (2:15-17). It wouldn’t be a big deal, but the first part of verse 28 says “After this”. To make things more confusing chapter three then starts talking about the great ingathering.

In reading through Joel, I don’t really think that it would be a very good source for setting up a continuous timeline. It seems to refer, in some places, to events happening in Joel’s day, but then it equates them, or passes on to, other things that will take place in the future. It seems to deal with events during the tribulation period at the end of the premillennial kingdom, events at the beginning of the millennial reign, events at the great outpouring, and events at the great ingathering. Centuries of time are crossed between verses that seem to be tied together. If you read my article on “Two Major Turning Points in the New Testament,” you know that this is nothing unusual, as I gave the example there of a single verse in Isaiah that tied together in the same sentence events in Christ’s day and events at the time of God’s wrath thousands of years later. Christ, in His teaching, split them apart again. There is no rule of sequential reference in prophetic writings, particularly in a poetic writing like Joel’s.

Luke translates “after this” as eschatais hemerais in Acts 2:17, or “in the last days,” which makes this “after this” to be referring to a particular time, not necessarily to the time following verse 27. I don’t think we can establish a definite time link between these two verses.

I don’t think we can establish one continuous timeline throughout this book. It refers to multiple events at multiple stages of the kingdom of God. Joel 3 seems to talk both about the great ingathering and the great tribulation.