Exodus 12:2

...................... In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house:

John 12:12

On the next day much people that were come to the feast, when they heard that Jesus was coming to Jerusalem

The Christian Church misses so much by not knowing the details of Jewish festivals. This Exodus passage provides details of Passover. On the 10th day of Nisan, the Jews were to select a lamb and follow the rest of the instructions which included inspecting the lamb and slaying it. The lamb was to be selected, then inspected for four days, and finally slain.

The John passage records the day that Jesus entered Jerusalem. His entry is on the 10th day of Nisan in accordance with Jewish Passover. They called it "Lamb Selection Day." Jesus did not go into Jerusalem looking for a lamb.  His entry was a strategic way of announcing himself as The Lamb that others should select. 

In keeping with Passover, Jesus entered Jerusalem on "Lamb Selection Day." He was later inspected by Annas, the Sanhedrin, Herod and Pilate. Once the inspection was over, the lamb had to be slain. While the Jews were in the temple slaying lambs, Jesus was being slain at Calvary.  Josephus said that 256,500 lambs were slain on the day Jesus was crucified. There was so much blood in the temple that they dug trenches and used water to wash the blood out. While blood and water flowed from the temple, a soldier had taken a spear and thrust it into Jesus side releasing blood and water.  

256,500 lambs died for nothing.  One died for all.  Jesus is the right Lamb.