How do Full Preterists interpret the Millenial Kingdom in light of the First Resurrection happening before the reign of Christ?

Revelation is apocalyptic language and is often interpreted as the most difficult book of the bible to understand. However, I find there are valuable details that should inform our understanding of eschatology. For example, Revelation 20:4-5 states: >**4** I saw thrones on which were seated those who had been given authority to judge. And I saw the souls of those who had been beheaded because of their testimony about Jesus and because of the word of God. They had not worshiped the beast or its image and had not received its mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years. **5** (The rest of the dead did not come to life until the thousand years were ended.) This is the first resurrection. While this text includes language that should not be taken literally (like the 1000 years often meaning "a very long period of time" in the Hebrew culture of the time), this still informs us of two things: 1. There **must** be a resurrection that kicks off the millennial kingdom, as those resurrected individuals must reign during the millennium. 2. This resurrection is made up of those who have lost their life due to their testimony of Christ. I understand that Full Preterists claim the millennial kingdom began in 30 AD. However, I do not understand how they interpret the first resurrection of those who died for their testimony of Christ (no one had yet died for their testimony of Christ). I believe 1 Thessalonians 4:16 further addresses this issue: >For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. I've heard the argument that the first resurrection is the resurrection of our spiritually dead souls to the life of salvation, but both Revelation 20 and 1 Thessalonians 4 allude to the "dead in Christ". If we are speaking of spiritual death, then we must assume you can be spiritually dead (unsaved) in Christ.