So they show that the "day" of judgment can last 1000 years.OK, there are lots of verses about judgment. How do you relate any of the ones that you just quoted as "occurring when Christ returns"?
Most of those occur at least 1000 years after Christ returns. Certainly eternal judgement is after the millennial kingdom.
But besides that, there are two times of judgment given in Rev 20, one at the beginning and one at the end of the 1000 years.
Revelation 20:4-6 (KJV) 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. 5 But the rest of the dead lived not again until the thousand years were finished. This [is] the first resurrection. 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.
You can see how these souls were judged worthy (based on the tribulations they endured) and that judgment came when they were resurrected, and then they began to reign with Christ for 1000 years.