“Ok, so when Christ said “on this day”, He didn’t really mean it?”
I’m sure he meant it. He didn’t, however, say the thief would be in “Heaven, on this day”, or “resurrected, on this day”, but that the thief would be in “paradise, on this day”. Most of the possible meanings of “paradise” are quite different than the traditional meaning of heaven. It may instead refer to the place known as Abraham’s bosom, or as Strong’s Concordance puts it:
“3) the part of Hades which was thought by the later Jews to be the abode of the souls of pious until the resurrection: but some understand this to be a heavenly paradise”
This would make perfect sense, because even if the thief did go to heaven on that day, Christ wouldn’t have been with him, since Christ went down to the grave that day, and not to heaven. The only way the statement really makes sense is if the “paradise” is part of the grave/sheol, and that is why Christ would be with him, since that was where Christ was headed as well.
True, the limbo of the Righteous or Abrahams bosom
I dispute the poster's point of saying that we won't go with Him until His return.