The church’s teaching on heaven is very clear. Yes, there will be a new heaven and a new earth when Christ comes again, and there will be a resurrection of the body on the last day, but this is not heaven as the church understands it. Let me explain.
We find numerous statements on the question in the Catechism of the Catholic Church. For example, in the section on the resurrection of the body we read: “We firmly believe, and hence hope that, just as Christ is truly risen from the dead and lives for ever, so after death the righteous will live for ever with the risen Christ and he will raise them up on the last day” (CCC 989).
That is, immediately after their death the righteous will begin their life with the risen Christ in heaven, not on earth, and then on the last day Christ will raise up the body to be reunited with the soul.
Also, “In death, the separation of the soul from the body, the human body decays and the soul goes to meet God, while awaiting its reunion with the glorified body” (CCC 997).
Two phases are indicated here. In the first phase, after death the soul goes to meet God in heaven. In the second phase the soul will be reunited with the glorified body at the end of time.
The catechism goes on to quote the first preface of Christian death in the Roman Missal: “When the body of our earthly dwelling lies in death we gain an everlasting dwelling place in heaven” (CCC 1012).
That is, immediately after death, while the body remains on earth, the soul already gains an everlasting dwelling place in heaven.
In the section on life everlasting, the catechism quotes the prayer of final commendation in the funeral liturgy: “May you live in peace this day, may your home be with God in Zion, with Mary, the virgin Mother of God, with Joseph, and all the angels and saints…” (CCC 1020).
Again, the prayer is that the soul will live in peace “this day” and that it will be at home in heaven with God, Our Lady, the angels and the saints.
Another clear statement on the question comes under the heading of the Particular Judgment: “The New Testament … repeatedly affirms that each will be rewarded immediately after death in accordance with his works and faith” (CCC 1021).
The soul will be rewarded immediately after death, not at the end of time. In this context we could also quote Our Lord’s words from the cross to the good thief: “Truly I say to you, today you will be with me in Paradise” (Lk 23:43).
One of the clearest teachings on the question is also in the section on the particular judgment: “Each man receives his eternal retribution in his immortal soul at the very moment of his death, in a particular judgment that refers his life to Christ: either entrance into the blessedness of heaven—through a purification or immediately—or immediate and everlasting damnation” (CCC 1022).
Again, eternal retribution comes at the very moment of death. As we know, entry into heaven can be immediate or preceded by purification in purgatory, and entry into hell is immediate.
As regards what heaven will be like, the catechism describes it in terms of a spiritual state of union with God, not of a heaven on earth: “This perfect life with the Most Holy Trinity—this communion of life and love with the Trinity, with the Virgin Mary, the angels and all the blessed—is called “heaven.”
Heaven is the ultimate end and fulfilment of the deepest human longings, the state of supreme, definitive happiness” (CCC 1024).
So, we won’t have to wait until the end of the world and the Second Coming of Christ, whenever that might be, to enjoy heaven. It comes immediately after death. And it is the spiritual state of heaven as we know it.