You “suppose”? Did Peter “suppose” when he said, “THIS is that which was spoken of”? No, he was speaking by the Holy Spirit when he explained:
“For these are not drunken, as ye suppose; seeing it is but the third hour of the day. But this is that which hath been spoken through the prophet Joel”
Those who were supposing were wrong, and Peter corrected them.
That prophecy was fulfilled on the day of Pentecost. That’s not supposing. We know it’s true because the Holy Spirit tells us so.
Are you saying the “great and manifest day of the Lord” has already come? If the apostles and disciples at Pentecost were living in the “last days”, even more so are we.