I didn't think you believed in a literal 1000 year reign, I don't. And if you read these verses as exactly as they are written, BOTH groups are the 1st resurrection. The resurrected saints who had not worshipped the beast AND the rest of dead that lived not again until the thousand years were fininshed... BOTH of these are the first resurrection.
(Rev 20:4) And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
(Rev 20:5) But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.
(Rev 20:6) Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
(Rev 20:4) And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
(Rev 20:5) But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.
(Rev 20:6) Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
I further believe that the end of our age is nearing. As the New Jerusalem, I believe it is when the Church is surrounded by the evildoers in the world and when we've lost our voice and influence that the world will spin out-of-control, kind of like what is happening now. When this happens and the Church has been silenced or taken over to the point that the message of salvation has been replaced by secular immorality that God will intervene and fire will come down from heaven and devour the evil then the next age will start. We have no clue what that age will be like. In the meantime, heaven is open to each believer upon death. We have individual resurrections as the writer of Hebrews taught.