Marulus,
Look at the complete quote from the Catechism. You should really take the time to think through this and not simply to find quotes that you can rip out of context - like the Dimonds - to justify a position you've committed yourself to beforehand.
You quoted the language in green. You have, of course, to read that consistently with the highlights in the first paragraph in red.
Strictly speaking, following the way you want to read it, the OT saints and St. Dismas didn't enter heaven until the Resurrection. And yet the Catechism says "at once" they experienced "the vision of God" when Christ descended to them before His Resurrection. What is heaven before the bodily resurrection at the end of time at the general judgment if not the "vision of God," i.e. the beatific vision?
In light of the first paragaph, I would say the catechism is using "death and Resurrection" as a kind of conflation of distinct events essential to our salvation and entry into heaven to refer to Our Lord's singular work at the end of the original Holy Week in Jerusalem that opened heaven for us. As the Catechism says, the OT saints "obtain their salvation through the benefit of His Passion."
There is nothing implied in the first paragraph about the OT saints, and St. Dismas, waiting around for another 36 or 48 hours or so until achieving the "vision of God" in paradise. On the contrary, it sounds rather like it was immediate upon Our Lord's visiting them.
Haydock interprets it that way when it says, in the annotation to Luke 12:43, that:
I have actually arrived at the correct position due to the evidence and I am not even committed to it absolutely because the question is irrelevant to BoD.
While I understand your position just fine, it seems you are the one who has failed to do his due diligence and actually ascertain what the Dimonds say, as well as read carefully what I have said.
As I have quoted already:
MFHM: Our Lord hadn’t even yet ascended to Heaven on the Sunday of the Resurrection. It is therefore a fact that Our Lord and the Good Thief were not in heaven together on Good Friday; they were in the Limbo of the Fathers, the prison described in 1 Peter 3:18-19. Jesus called this place Paradise because He would be there with the just of the Old Testament.
My position, and the Brothers', is exactly the one you for some reason think I reject, that Abraham's bosom became Paradise, in a sense, in the presence of Our Lord.
What I am contesting is that St. Dismas and the other saints entered Heaven, the place, before Christ's ascension.
I'm receiving mixed signals so I hope that is your position as well but that you just misunderstood me.
P.S. The 'at once' refers to after Christ descended into Abraham's bosom, so I don't see what is supposed to be its significance.