The fact that Jesus has fulfilled all the feasts on the exact day so far in progression is most significant.
Passover,
Unleavened Bread,
Firstfruits,
Pentecost all happened on the exact feast day.
Based on that pattern you would expect the three yet to be fulfilled would happen in the same sequence.
Rosh Hashanah(rapture of the church),
Day of Atonement(start of tribulation, two witnesses to Jerusalem and 144,000 Jews believe in Jesus),
Feast of Tabernacles, (1000 year reign of Christ) - then the final judgment, new heaven and earth.