Jewish History Begins with the Seder

The first Seder takes place before the event which it commemorates - the Exodus from Egypt! Why did God command the Jews to celebrate the Exodus before it happened? Why is the first mitzvah how to make a calendar?

World history follows causality; regarding the Exodus from Egypt and Jewish History in general, the latter impacts the former. What is the difference between the year that begins in Nissan vs. Tishrei?

Delivered at the OU Israel Center, January 8th, 2019 (2 Shevat 5779)