Albert Barnes on Luke 22:17

And he took the cup and gave thanks. This was not the sacramental cup, for that was taken after supper, Lk 22:20. This was one of the cups which were usually taken during the celebration of the Passover, and pertained to that observance. After he had kept this in the usual manner, he instituted the supper which bears his name, using the bread and wine which had been prepared for the Passover, and thus ingrafted the Lord's Supper on the Passover, or superseded the Passover by another ordinance, which was intended to be perpetual.