It seems when John saw the 24 elders wasn’t there a mention of a vision? So would it be possible the end time visions seen by John the 24 elders, the saints under the throne were visions of future events as the book of revelation is written? This has not yet come to pass. But our Lord is soon in coming all the prophecies are up!!!!!! It won’t be long. But what I have read will come to pass heaven is ready to receive us. One third of the heavens were swept out with Satan. Are we the one third to take their place? Only wonderingâ€¦..
By all indication, the 24 elders were already in heaven in the present back when John saw his vision of the throne room. Just as the Messiah was already ascended and in his place there. If we take these to be men as the evidence points to, then this makes more sense then saying this in some yet future resurreciton/rapture of only 24 people. I still think the best explanation is that these 24 were “raptured” at the time Jesus was to fulfill the Wave Sheaf prophetic rehearsal of Leviticus 23.
If I understand your other question correctly you are asking if we are going to heaven to replace the 1/3 of the angels who Satan marshalled in rebellion against God (Revelation 12)? The purpose for us going to heaven is not because it needs population but because we are not “appointed to wrath” (1The 5:9). Jesus indicated that the rapture would be right before God’s seven bowls of wrath fell. And by the way, the angels are still in heaven today because as Job and Revelation 12 indicate, their casting down with Satan after being banned from heaven is not until the start of the Great Tribulation of his wrath (the reason for the “woe, woe, woe” mentioned in Revelation 12 is the same as the three woes of the 5th, 6th, and 7th trumpets).