The Scriptures above referred to, together with many others, show that Christ will reign during the Millennium, and we all know Christ has not reigned yet. If Christ was reigning now, we would not have the great systems of evil in the earth, for the Scriptures declare that when “His judgments are in the earth then the people shall learn righteousness” (Isaiah 26:9). The texts in the question declare “the dead in Christ shall rise first” at his coming. In harmony with this, we see then he will take unto himself his great power and reign, as set forth in Revelation 11:17,18. Jesus himself declared (Matthew 25:31) his reign would follow his second advent.

Additional Resources:
Christian Questions Podcast
Episode #1185: “What Are the True Reasons for Jesus’ Return to Earth?”
Uncovering the remarkable and inspiring mission of Jesus’ return
Preview Video
CQ Rewind Show Notes

Episode #1194: “Could Jesus Return Without You Knowing?”
Revealing the three scripturally progressive phases of Jesus’ return
Preview Video
CQ Rewind Show Notes

PDF Booklet: Our Lord’s Return