When was this carved in stone?
It was carved in stone far earlier than your 19th century modernist philosophy of the pre tribulation rapture.
1800 years earlier
Recently discovered Syriac fragments of stories about the Assumption of Mary have been dated as early as the third century. And there are undoubtedly more manuscripts to be found. It must be remembered that when we are talking about these “Transitus stories,” we are not only talking about ancient manuscripts and fragments of manuscripts, but we are talking also about two different “families” of manuscripts written in nine languages. They all agree on Mary’s Assumption and they presuppose that the story was already widely known.