Jude 1.14,15 says Christ will return with only tens of thousands of saints. Let's be generous and say at most that is the 144,000. It could be referring to th 144,000 only that will return because they are still virgins (Rev. 14.1-5), and they are closest to Christ.

But if there were 50 billion souls (as a best guess) since Adam, and the savings ratio is 1 in 250 (based on the size of the new city), that is 200,000,000 million saved from the OT and dispensation of grace.

If only 1/7th of those are overcomers that still leaves 28.5 million overcomers.

The way to make sense of this is to say the 144,000 will return with Christ to put down Satan and his minions. Then, once that judgment occurs, from the 1260th to the 1290th day, then the 28.5 million will take their reigning positions over the cities of the nations.