At this moment, we are in the Jewish month of Tishri. It is the first month of the Civil calendar and is the 7th month.
Research quickly shows its deep religious significance, including solemn feasts such as the Day of Atonement, Gedaliah, etc.:
I am fully aware that I am swimming against the mighty tide, but I suggest that symbolically for Christendom, that the "sacrifice" of Jesus relates to the Jewish festivals of Tishri (Sept/Oct) more than it does to the Passover at Nisan (March/April).
Terms such as "propitiation", "mercy seat", "high priest", "atonement", all reference Tishri. And palm fronds would be available for the crowd at the end of Summer.
Also: did any "Last Supper/Memorial" actually take place, let alone in Nisan (March/April)?
Apostle Paul was the earliest NT writer. He claims that he obtained his information directly from "the Lord", not from any human source. It is he, therefore who introduced the idea of this "Final ('Memorial') Meal". It is he who described events taking place at that Meal. The later writers of the Gospels copied and embellished Paul's creative imagination.
Not one NT writer was present at that Meal yet they were able to recount events in some detail.