The Jewish year can be viewed as a trial
When Jesus began His ministry John said "behold the lamb of God". That told us exactly how and when He would be put to death. The Passover was instituted by God to display the sins and crimes of Egypt. They had killed those little babies, which are likened to lambs. Jesus death on the cross displayed the sins and crimes of the Romans and Jews. It was the "videotape" evidence of their guilt. Maybe many of the other trials and convictions would have been harder to prove they were guilty. For example we have videotape evidence of a cop shooting a thirteen year old kid, but the kid was holding a gun which he had fired, the kid was out at 2am with another man who was a convict. So as terrible as that video is it isn't perfect evidence of a crime the way Jesus' crucifixion was.
That said, Jesus said that we were His witnesses. During the Passover you don't just have the lamb, you also have the witnesses. These are the ones who have put the blood on the doorpost. Our mouth is our "door" to our heart. The eyes and ears may be windows, but the mouth is the door.
Deuteronomy 6:9 You shall write them on the doorposts of your house and on your gates.
How do you write the law of God on the doorposts? The law of God is a portrait of God, the blood of the lamb is also a portrait of God, an expression of God manifested in the flesh. The witnesses need to have Jesus, the incarnated word of God, the Lamb of God who died for us, on their mouth.
Hosea 6:2 After two days he will revive us; on the third day he will restore us, that we may live in his presence.
The age of grace is two thousand years which to God is like two days. This age is like a trial where the evidence is presented that this age is corrupt, the rulers are evil, and they need to be judged. We are the witnesses in this trial.
Revelation 6:9 When he opened the fifth seal, I saw under the altar the souls of those who had been slain because of the word of God and the testimony they had maintained. 10 They called out in a loud voice, “How long, Sovereign Lord, holy and true, until you judge the inhabitants of the earth and avenge our blood?” 11 Then each of them was given a white robe, and they were told to wait a little longer, until the full number of their fellow servants, their brothers and sisters, were killed just as they had been.
This is the conclusion of the prosecution. Once the prosecution rests the defendants still have an opportunity to present a defense. Therefore after they give their testimony they still need to wait a little longer until the trial is concluded and there is a judgement. However, when a guilty party has no defense they will often do something desperate like "kill more servants just as the others had been killed".
The Jewish year begins with the Passover lamb being slain, the crime is committed and the witnesses are there. To be a witness is to eat the bread of affliction during the feast of unleavened bread. After that you present the law enumerating the charges and offenses, the feast of Shavuot celebrates the Israelites coming to Mount Sinai where the Law was given after the Passover feast. Then when the trial is concluded you have a deliberation of the Jury. This is called "the days of awe" or "Jacob's trouble". It is the ten days from the Festival of Trumpets to the day of Atonement which is when the judge announces the verdict. The Jewish year can be viewed as a trial.
So then let's return to our role in this trial, we are not the lamb of God but there have been many martyrs and their blood is also part of the evidence against this evil age. If you have an evil ruler on trial for murder it is very relevant if there are multiple offenses of this crime that are similar. If you had a serial killer it would be very important to present evidence not only of Jesus crucifixion but also of all the other crimes and sins they have committed. Therefore the Jewish year does not just have "the Passover" but there is also a second Passover for those who missed the first one.
Revelation 6:12 I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red, 13 and the stars in the sky fell to earth, as figs drop from a fig tree when shaken by a strong wind. 14 The heavens receded like a scroll being rolled up, and every mountain and island was removed from its place. 15 Then the kings of the earth, the princes, the generals, the rich, the mighty, and everyone else, both slave and free, hid in caves and among the rocks of the mountains. 16 They called to the mountains and the rocks, “Fall on us and hide us from the face of him who sits on the throne and from the wrath of the Lamb! 17 For the great day of their wrath has come, and who can withstand it?”
This is the point in the trial when the criminal knows he is doomed. I suspect that this is immediately after the first rapture. But we are given a very interesting clue, "the whole moon turned blood red". That will not happen 50 days after the Passover because the Passover is always on a full moon. You will not get a full moon 50 days later. Nor will it happen on the Festival of Trumpets because that is always on a new moon unless it is a jubilee year in which case it will be ten days later, still not a full a moon. Nor will it be on the feast of atonement because that is always ten days after the New moon.
Revelation 6:7 After this I saw four angels standing at the four corners of the earth, holding back the four winds of the earth to prevent any wind from blowing on the land or on the sea or on any tree. 2 Then I saw another angel coming up from the east, having the seal of the living God. He called out in a loud voice to the four angels who had been given power to harm the land and the sea: 3 “Do not harm the land or the sea or the trees until we put a seal on the foreheads of the servants of our God.”
Look at this! Passover refers to God standing over the house to prevent it from being broken into by the avenging angel. Here we see the exact same thing. Also we are told that the Lord's return will be like a thief in the night for those who are not paying attention. The only Jewish festival with a "thief in the night" is Passover, the avenging angel went through all the houses of the Egyptians and stole the firstborn of man and beast.
Another interesting point about Passover, they celebrate the meal the evening before the full moon, then they leave Egypt immediately after and that night you have your full moon, the first night in the desert. Likewise we see the fifth seal with the blood of the martyrs before the sixth seal when we see the blood moon.