Palm Sunday occurred during Passover week. This is the week the Jewish people celebrated the sacrificing of the Passover lamb. And this would be the week The Christ (our Passover Lamb) was crucified for the sins of the world.
It is important to realize, and this is the theme for the day in understanding the entrance of Jesus into Jerusalem. God works not in hours and minutes; He works in seconds. Everything is designed and planned by Him, and He is in control of all things. Nothing happens by accident. He has everything under control. He knows all things. And He brings about His purposes to the exact second that they are to happen.