Covenant Theology postulate either Amillennialism or Post Millennialism.
I like Postmillennialism. The main key take away is that Christ reigns now over all nations and that scale of reigning will increase accordingly to full reign when He returns. That’s new to me! And that’s really empowering comforting and consoling when you see wat just broken out in Ukraine by the aggressive big bully of Russia and hundreds already killed and hundreds of thousands has fled as refugees from Ukraine. So we know Christ reigns over that!! As well! But how come the war is still on of Christ is reigning for example? Well that’s precisely what I just said the reign of Christ is progressive! Increasing all the way till end time when he returns.
The main driver for this is the verses:
Isaiah 2:2–3 (ESV)
2 It shall come to pass in the latter days that the mountain of the house of the Lord shall be established as the highest of the mountains, and shall be lifted up above the hills; and all the nations shall flow to it, 3 and many peoples shall come, and say: “Come, let us go up to the mountain of the Lord, to the house of the God of Jacob, that he may teach us his ways and that we may walk in his paths.” For out of Zion shall go forth the law, and the word of the Lord from Jerusalem.
About Isaiah 2:2-4, Calvin had the following to say: “ . . . while the fullness of days began at the coming of Christ, it flows on in uninterrupted progress until he appears the second time for our salvation.” During this time “the church, which had formerly been, as it were, shut up in a corner, would now be collected from every quarter . . .. The Prophet here shows that the boundaries of his kingdom will be enlarged that he may rule over various nations. 
To me, the mountain of the house of the Lord shall be the highest of the mountains! All the nations shall flow to it. This is speaking prophetically before Christ returns. Because when Christ returns, there is only one mountain, the mountain of the Lord! Therefore the thesis is that the current world, earth shall see the establishment of the church of Jesus Christ stronger and stronger and bigger until the church of Jesus becomes the tallest and highest of all mountains of the world. Mountains here can metaphorically refer to institution, power, or organization of sort.
Greg Bahnsen also writes on Calvin, “The Prophet has in his eye the whole reign of Christ, down to its final close, which is also called ‘the day of renovation and restoration.’ (Acts iii.21)” “The glory of God shines . . . never more brightly than in the cross, in which . . . the whole world was renewed and all things restored to order.” 
Acts 3:20–21 (ESV)
20 that times of refreshing may come from the presence of the Lord, and that he may send the Christ appointed for you, Jesus, 21 whom heaven must receive until the time for restoring all the things about which God spoke by the mouth of his holy prophets long ago.
Heaven must wait until the time of RESTORING ALL the things which God spoke through his prophets long ago.
The word “until” is important. That means the restoration of all the things prophets prophesized in the OT and the NT alike. What’s this restoration? Restoration to pre-fall! To paradise. SO I would argue that based on this, the pre return of Christ for the end time will usher in paradise. I used to think that the world will be so rotten as wickedness increases etc., and Christians remain the minority, liberally hanging on to our faith before Christ return.
Matthew 24:9–14 (ESV)
9 “Then they will deliver you up to tribulation and put you to death, and you will be hated by all nations for my name’s sake. 10 And then many will fall away and betray one another and hate one another. 11 And many false prophets will arise and lead many astray. 12 And because lawlessness will be increased, the love of many will grow cold. 13 But the one who endures to the end will be saved. 14 And this gospel of the kingdom will be proclaimed throughout the whole world as a testimony to all nations, and then the end will come.
You see how much oppositions and lawlessness (wickedness) coming to this world in end time. So don’t be caught off guard. Jesus actually said, the love of MANY will grow cold. But more importantly the Lor balanced it up with the last line:
This gospel of the kingdom will be proclaimed throughout the WHOLE world, and then the end will come! So before the end comes, when Christ returns, the gospel will be preached to ALL nations, through the whole world! Some theologians refer to AD 70 when Paul brought to the different parts of Samaria, Judea, etc. That, to me, is definitely NOT the ends of the world.
Conclusion: Wickedness, lawlessness will increase till the end of the world, but that the same time gospel will reach the whole world.
If you synch that last statement of Christ on gospel proclaimed to the whole world, with Acts 3:
21 whom heaven must receive until the time for restoring all the things about which God spoke by the mouth of his holy prophets long ago.
Not just proclaimed to the whole world, but restoration of ALL things of the whole world, we cannot but assert that Gospel will change the whole world, and all things will be restored. How can restoration start if the gospel doesn’t impact souls? Doesn’t change people’s hearts?
Therefore the Gospel must be preached to the whole world, and changes will become more and more apparent as more nations, more tribes turn to Christ, though at the same time, those who reject Christ, will become more lawless. It will culminate in the war f Armageddon so to speak before Christ returns!
 Greg Bahnsen, The Reformed View of Postmillennialism