Acts 2:16-21,
Peter said, V 16, "This is that which was spoken by the prophet Joel."
"This is", in other words, this is the fulfillment of that prophecy.
V 17, "The latter days", so since the Day of Pentecost, it has been the latter days.
V 17-18, The things mentioned here are confirmed in 1 Cor., in the church, starting at Pentecost.
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V 19-20, When do these events occur?
35-37 years in the future at the dest of Jerusalem? Or 2000 years later?
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Since Peter said that the Day of Pentecost was the fulfillment of Joel, you would think that the fulfillment of the dest of Jeru. was not far off time in the time line.
The dest of Jeru. has been a prophecy of Ezek and others, Ezek 5:5, 10, 12, 16-17. Lk 21:20-24.