The Dolorous Passion of Our Lord Jesus Christ by Blessed Anne Catherine Emmerich mentions that Jesus and his disciples celebrated the Passover a day before the rest of the Jews did. Is this true?
The Dolorous Passion of Our Lord Jesus Christ is not a reliable guide to the events of the passion, death, and resurrection of Christ. The book is attributed to Anne Catherine Emmerich but contains enough theological problems that the attributed writings were specifically excluded from the study of Emmerich’s life before her cause for beatification proceeded. The book gained public attention when Mel Gibson used it as a source for his movie The Passion of the Christ. While it was fine for Gibson to use theologically unproblematic stories from the writings as literary embellishment to the Gospel narratives, the writings cannot be considered authoritative.
As to the question of whether Jesus ate the Passover meal with the disciples early, this is something we do not know for sure. It is implied though by the Gospel narratives, which recount that Jesus was crucified on the day of preparation for the Passover (John 19:14), which would have been during the day before the Seder meal was celebrated by the Jews. In Judaism, the holy days start at sundown the previous day. So, if Passover began on Saturday that year (John 19:31), the Jews would have prepared for it during the day on Friday and eaten the Seder meal on Friday evening. Since it was important to Jesus to share the Passover meal with his disciples before his crucifixion (Luke 22:15–16), by his authority as God the Son he could have chosen to eat the Passover meal a day early in anticipation of the traditional start of the Passover (Matt. 7:28–29).