What you are saying is something that you have incorrectly concluded. You have no scriptural support. How do I know that? Because scripture says that the great multitude is before the throne which is in heaven.
Revelation 7
9 After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;
You should let scripture draw your conclusions.
You should take your own advice. You think the throne will only be in heaven? Rev 7 is the same timeframe as Rev 21, long after the GT and second coming and even the GWTJ.
Revelation 21 occurs at the end of the 1000 years. If you are looking for the great multitude you need to look in Revelation 19
Revelation 19
6 And I heard as it were the voice of a great multitude, and as the voice of many waters, and as the voice of mighty thunderings, saying, Alleluia: for the Lord God omnipotent reigneth.
These return with the Lord with the armies of heaven with the Lord.
That isn't a great multitude at all. It's the voice of God.
Whoever is following this might want to read this very long commentary:
Revelation 7:9 After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;
Revelation 7:10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
Revelation 7:11 And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God,
Revelation 7:12 Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen.
Revelation 7:13 And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they?
Revelation 7:14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
Revelation 7:15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
Revelation 7:16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat.
Revelation 7:17 For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.
Here is a major jump in chronology. John now sees a huge multitude of people, all arrayed in white robes which symbolizes righteousness and that they are in spiritual bodies. They have come through "great tribulation, and have washed their robes, and made them white in the blood of the Lamb" which places this past the tribulation period and into the eternity. This multitude has overcome and have been judged to life.
Revelation 7:10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
As you can see, the throne is not empty. God the Father is there upon it, and the Lamb, Jesus Christ, is next to Him and He will be on the right side of the throne.
This is a major "clue" to documenting just when this happens, for there are only certain times that the full Godhead (where they are, the Holy Spirit is naturally present) will be together like this, especially with a numberless crowd in the white robes of righteousness standing before them and giving praise. In short, this is definitely not happening right after the tribulation but a time after that. The next verses will help to establish just when this actually is.
Revelation 7:11 And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God,
Again, this would not be happening directly after the tribulation had ended, which would be the beginning of the Millennium for at that time Christ leaves heaven and takes most if not all of heavens angels and returns to the Earth at the 7th trump. Either this verse happens before that happens in heaven, or this is happening the next time Christ is together with God the father which wouldn't be until judgement day, and all time after that.
Revelation 7:12 Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen.
This is comparable to this:
Revelation 5:12 Saying with a loud voice, Worthy is the Lamb that was slain to receive power, and riches, and wisdom, and strength, and honour, and glory, and blessing.
Revelation 7:13 And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they?
Ok, this is where it gets interesting.
Revelation 7:14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
It is commonly assumed that this coming out "of great tribulation" is a reference to the tribulation of the antichrist and refers to no other tribulation. It actually means any and all tribulations, that these overcame all of them rather than a specific one. There are several "tribulations" that these shall endure through in order to be standing here in white robes praising God. The first one shall be that tribulation hour of the antichrist, then any who took satan's mark will suffer through God's tribulation, which will be all peoples except the elect which is a considerably smaller number than this multitude, and then there is that last testing of satan when he is released from the pit at the end of the Millennium and will convince and persuade a great numberless multitude to follow him to war with God. Unfortunately if they choose satan at that time, they shall be judged according to that decision for judgement starts right after that.
So, there are several times of tribulation, and even that 1000 year period could be considered another time of tribulation for those who must endure through the teaching and the disciplining.
tribulation
2347
2347 thlipsis {thlip'-sis}
from 2346; TDNT - 3:139,334; n f
AV - tribulation 21, affliction 17, trouble 3, anguish 1,
persecution 1, burdened 1, to be afflicted + 1519 1; 45
1) a pressing, pressing together, pressure
2) metaph. oppression, affliction, tribulation, distress, straits
Tribulation is just a really rough time, of varying degrees. A time of distress, a time of stress, pressure and so forth.
Revelation 2:22 Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds.
Revelation 2:23 And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works.
That is God's tribulation and its something to be avoided.
Revelation 7:15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
If this supposedly happens right after the end of the first tribulation of the antichrist, then this is within the time of the Millennium , the 1000 year reign of Christ. Do that many people have access to the temple in the Millennium ? I'm afraid not, for only the priests of the Zadok shall have access to the temple during that time. There shall not be such a large number of people who can approach the throne, in front of the full Godhead who are clothed as they are being symbolic of purity and righteousness. It also says the one on the throne dwells among them. When does God the Father dwell among mankind like this? The Eternity!
Rev_21:3 And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God.
Revelation 7:16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat.
This should sound familiar. When is there a time that we should not hunger nor thirst anymore?
Revelation 21:1 And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
Revelation 21:2 And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.
In chapter 21 we have passed the time of judgement are are now being given a glimpse of the eternity in the new age with the new Heaven and the new Earth ages beginning.