Luke 22: The Passover Meal

It is confusing when Jesus ate the Passover Meal: was it when the lambs were sacrificed (Nissan 14) or was it one day before (Nissan 13) ? Did Jesus die when the lambs were being sacrificed (Nissan 14) or did Jesus die one day after (Nissan 15) ?
Jesus is the lamb of the Lord who takes away the sins of the world, thus, it is a great sign of the Lord that Jesus had been crucified on the Passover.
The Passover Meal is also very important.
Jesus knew on that day that He was to be crucified, so we read:

17-18 Taking the cup, he blessed it, then said, “Take this and pass it among you. As for me, I’ll not drink wine again until the kingdom of God arrives.”
19 Taking bread, he blessed it, broke it, and gave it to them, saying, “This is my body, given for you. Eat it in my memory.”
20 He did the same with the cup after supper, saying, “This cup is the new covenant written in my blood, blood poured out for you.

How can we deny that Jesus knew about his crucifixion when every Christian church celebrates the Holy Communion?
Christianity is very different from all others religion. We drink the blood of Jesus that was poured out for us. This is the new covenant.