And it shall come to pass afterward that I will pour out My Spirit on all flesh; your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions. And also on My menservants and on My maidservants I will pour out My spirit in those days. And I will show wonders in the heavens and in the earth: blood and fire and pillars of smoke. The sun shall be turned into darkness, and the moon into blood, before the coming of the great and terrible day of the Lord. And it shall come to pass that whoever calls on the name of the Lord shall be saved” (Joel 2:28-32).
First, "And it shall come to pass afterward that I will pour out My Spirit on all flesh; your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions. And also on My menservants and on My maidservants I will pour out My spirit in those days." This part happened during the days after Christ's return to Heaven and during the Apostolic days.
"And I will show wonders in the heavens and in the earth: blood and fire and pillars of smoke. The sun shall be turned into darkness, and the moon into blood, before the coming of the great and terrible day of the Lord. And it shall come to pass that whoever calls on the name of the Lord shall be saved." This part is yet to happen, and will happen at the Return of Christ after the Tribulation Period.