In says in the Catechism:
Scripture calls the abode of the dead, to which the dead Christ went down, “hell”— Sheol in Hebrew or Hades in Greek—because those who are there are deprived of the vision of God. Such is the case for all the dead, whether evil or righteous, while they await the Redeemer: which does not mean that their lot is identical. (CCC 633)
This says “all the dead” went to “hell”, which means that noone was in heaven before the death of Jesus.
So in the Old Testament it tells of prophet Elias going to heaven.
And in the New Testament it tells of Moses and Elias appearing in splendor with Jesus on the Mount of Transfiguration. Appearing as they did in splendor seems to imply they were in heaven.
Does anyone have an answer?