In my last thread, "When did Jesus receive the Revelation scroll/book?" the thief on the cross went to Paradise with Jesus on the day that Jesus descended into hell. Even the Paradise created for man was not with God at that time, which would be consistent with the sin curse of man inflicting all creation.
Acts 2:31 "He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption."
Luke 23:43 "And Jesus said unto him, Verily I say unto thee, Today shalt thou be with me in paradise."
I agree with human rebellion separating mankind from God's Kingdom.
I agree that mankind was separated for a time from the Garden of Eden/Paradise.
I deduce that the Garden of Eden/Paradise was separated from God's Kingdom in heaven because of sin until the time of the new song, the time Jesus returned to heaven.
I also agree that the "New Song" represents a 2nd chance for Man to return to Eternal Life with God.
Now there are 2 questions that may have the same answer:
When did mankind's separation from Paradise come to an end? (Since the thief went to Paradise in hell with Jesus)
What does the first song represent?
The 1st song was, I think, in Eden. Also, Israel had a 1st song under the Law of Moses. In each case, "paradise" was lost--the blessings of perfect obedience were lost. But in each case, a measure of paradise was reissued, on a lesser level, as a relationship with God with only limited blessings.
Perhaps we can over-literalize these visions and symbols, since they are designed to show the story of redemption generally, instead of giving exact timelines or chronologies? The details are, as you seem to suggest, absent, forcing us to either fill in the details or accept the statements on their face.
To be with the Lord in a state of being blessed is, by definition, "paradise." It is, more technically, the place on earth where blessings may be experienced. When Jesus told the thief that he would be with him in Paradise, he was simply saying that the thief would continue to be with him and would be with him in a blessed state of acceptance, even if not yet on the earth.
I think you're right to ask the questions, however, because there was certainly a difference in the position of the dead, saint and sinner, both before the cross and after the cross. Jesus visited the place where all the dead were, both righteous and unrighteous, to declare deliverance from death for all.
But there is a 2nd death that is imposed upon the unrighteous, so that being in a state of separation from blessings on earth they will continue to be thus separated. On the other hand, Jesus went to the place of the dead to assure the righteous that they will experience victory over death and thus obtain a new Paradise with Christ when they are raised from the dead.
Christ declared to the saints this victory over death, but they have remained in a state of death, not having immortal bodies yet. They are, however, in a blessed state of fellowship with the Lord, though they only are given legal status that enables them to be certified owners of new immortal bodies in the future.
In sum, I see little difference between Paradise with God before the cross and Paradise with God after the cross, inasmuch as Paradise is being with God, and the saints never lose this place. But technically, Paradise is a blessed state on the earth with God, which suffered a setback at the Fall of Man.
Paradise was always a renewed offer to Man after the Fall, even if it was a limited and restricted offer. A "New Song" was always made available to us by God. Man never had to be completely separated from God, but could continue to obey God and thus walk with God and be blessed by Him on earth.
Although Man was generally cast out of Paradise on earth, Grace was always active to reestablish Man's ability to remain with God in a blessed state. The Law was given to perpetuate Israel's relationship with God, which allowed them limited blessings through obedience.
But at the cross, it was determined that no measure of human obedience could obtain the kind of Paradise God originally wanted to give Man, an eternal state of blessedness with Him forever, or Eternal Life. What saints got after the cross was the reassurance of their continued relationship with God, with the legal guarantee that they will return to blessedness with Christ on earth. Since the departed saints continue to be with Christ, they are already, to some extent, in "Paradise." But in the future we will get "Paradise Restored." :)