"Christ our ........................ has been sacrificed" (5:7) -- Christ died on the Passover day
"Christ the .........................." (15:23) -- Christ rose on the barley firstfruits day
"Stephanas, the ............................" (16:15) -- Christianity had its first converts on Pentecost Day (Acts 2), which was the wheat firstfruits day.
Note 1: Mathematically, the odds of those three events occurring on those three days is one in 365x365x365. This is one in about 50 million.
Note 2: The week-long festival of eating unleavened bread followed immediately after the Passover, just as Jesus disciples were in mourning immediately after the Passover.
Note: Just a trumpets warned that the annual "Judgment Day" was 10 days away, so certain signs (in Matthew 24:29) warned that the final "Judgment Day" was about to start.
Note: Just as the Jews lived away from home for a week, we will live away from our earthly home for 1000 years. And the Jews were told to do this "after you have gathered in your crops." Thus this parallels us being in Heaven after the Second Coming.
Note: Enemies tried to kill God's people, but the enemies were killed and God's people celebrated. Similarly, at the end of the 1000 years, enemies surround the Holy City to kill God's people. But they are destroyed and God's people "live happily ever after."