the Amil weakness is when it turns revelation 20:4 into souls of dead believers going To heaven to reign prior to the resurrection, as such supporting scripture is not found in the NT. Christ clearly gives authority over nations at His coming (revelation 2:25-26). Christ sat down on His Fathers throne after His resurrection, so why also wouldn’t the believer (revelation 3:21)? Christ clearly rewards at his coming (Matthew 16:27, Romans 2:6, 2 Corinthians 5:10, 2 Timothy 4:8, revelation 22:12). And I think, this is where the premil strength is, in its recognizing that this also seen as realized in revelation 20:4.
so it seems to me that there are “two stages” as you put it, however, I would argue they have been rolled into one, and seen through the lens of Christ’s resurrection. In other words , John is seeing, in a vision, stage 1: “already” (the spiritually raised and born again royal priest hood) and stage 2: “not yet” (resurrection of saints to reign with Christ and sit on His throne) as if they are the same stage. The fully realized promises to the saints seen fulfilled through Christ’s resurrection.
this would be consistent with Hebrew block logic, which doesn’t necessarily order events in chronological time, but instead by relation.
What’s interesting is that revelation 20:5 states “the rest of the dead did not come to life until after the 1,000 years was fulfilled”. This seems to be a reference to the end of the chapter, when death, hades, and the sea release the dead to stand before the throne of judgment. However notice, that the rewarding of the saints is NOT what is emphasized. Instead, the emphasis is on those being thrown into the lake of fire (2nd death).
so it seems the rewarding of the saints is emphasized at the beginning of the chapter, while the “repaying” of the wicked is emphasized at the end of the chapter, which is interesting as scripture declares God judges the righteous and wicked together at the final judgement: (Daniel 12:2, John 5:28-29, Matthew 16:27, Matthew 25:46, acts 24:15, 2 Corinthians 5:10, revelation 22:12).