After much research in-the-bible, I've come to understand that the Jewish date of Sivan 6 as Shavuot is incorrect. The true date of Shavuot (50th day after the morrow after the Passover) is Sivan 17. Here's that info for your perusal ;o}
===> Nisan 15, Israel departs Egypt, 430 years "to the day" from when they arrived ...
"Now the sojourning of the children of Israel, who dwelt in Egypt, [was] four hundred and thirty years. And it came to pass at the end of the four hundred and thirty years, even >>>the selfsame day<<< it came to pass, that all the hosts of the LORD went out from the land of Egypt. It [is] a night to be much observed unto the LORD for bringing them out from the land of Egypt: this [is] that night of the LORD to be observed of all the children of Israel in their generations. ... And it came to pass >>>the selfsame day<<<, [that] the LORD did bring the children of Israel out of the land of Egypt by their armies." {Exodus 12:40-42, 51 KJV}
^^^ THIS is where the Jews' err in their chronology for they only acknowledge 210 years, not the full 430! This error puts them short some 220 years! It's not the year "5781", it's closer to the year 6000 right now!
===> Nisan 15 (con't), the month of Abib (verified by the star Spica/Abib) ...
"And Moses said unto the people, Remember this day, in which ye came out from Egypt, out of the house of bondage; for by strength of hand the LORD brought you out from this [place]: there shall no leavened bread be eaten. >>>This day came ye out in the month Abib<<<." {Exodus 13:3-4 KJV}
===> Sivan 15, Israel arrives at Mt Sinai, three months "to the day" ...
"In the third month, when the children of Israel were gone forth out of the land of Egypt, >>>the same day<<< came they [into] the wilderness of Sinai." {Exodus 19:1 KJV}
===> Sivan 17, on the "third day" after arriving at Mt Sinai ...
"And the LORD said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes, And be ready against the >>>third day<<<: for the >>>third day<<< the LORD will come down in the sight of all the people upon mount Sinai." {Exodus 19:10-11 KJV}
1st day = Sivan 15 (to day)
2nd day = Sivan 16 (to morrow)
3rd day = Sivan 17 (the third day)
===> Sivan 17 (con't), Israel meets, and is betrothed to, God, notice the trumpet! ...
"And he said unto the people, Be ready against the >>>third day<<<: come not at [your] wives. And it came to pass on the >>>third day<<< in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the >>>trumpet<<< exceeding loud; so that all the people that [was] in the camp trembled. And Moses brought forth the people out of the camp to meet with God; and they stood at the nether part of the mount." {Exodus 19:15-17 KJV}
"And mount Sinai was altogether on a smoke, because the LORD descended upon it in fire: and the smoke thereof ascended as the smoke of a furnace, and >>>the whole mount quaked greatly<<<. And when the voice of the >>>trumpet<<< sounded long, and waxed louder and louder, Moses spake, and God answered him by a voice." {Exodus 19:18-19 KJV}
God gives Israel the 10 commandments, Israel in fear and rightly so!
"And all the people saw the thunderings, and the lightnings, and the noise of the >>>trumpet<<<, and the mountain smoking: and when the people saw [it], they removed, and stood afar off. And they said unto Moses, Speak thou with us, and we will hear: but let not God speak with us, lest we die." {Exodus 20:18-19 KJV}
===> The true date of Shavuot is Sivan 16-17 (sunset to sunset), NOT Sivan 6. It's worthy to note that Jesus resurrected on the "third day" after His passion (death) on Nisan 16/17 ... three months "to the day", "the self-same day", is Sivan 16/17 ... the day of Pentecost (Shavuot). Do y'all see a pattern here? I sure do!
The first trump(et) would have been when Israel was betrothed to God. I believe we, the church bride, are awaiting something similar that Paul called the "last trump", that we, the betrothed of Christ Jesus (Messiah Yeshuah), are longing to hear ... the day we meet our Bridegroom! Be ready, be wise, make sure your lamps are full of oil, lit, and you have an extra vessel of oil to go the distance.
"Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed." {1 Corinthians 15:51-52 KJV}
Maranatha to our Bridegroom, come Lord Jesus, come!