I realize that as Christianity grew from Judaism (Jesus came to fulfill the law) that the Lord’s day became celebrated on Sunday instead of the old Jewish Sabbath of Saturday. I also notice that the Jewish Sabbath begins at sundown on the evening before, i.e. Friday evening. Does that mean our Lord’s day, Sunday, begins on Saturday evening? If so, should we be practicing any special devotions on Saturday evening in preparation for attending mass on Sunday?
The Church currently recons a day as a 24 hour period beginning at midnight (cf. , 202.1Code of Canon Law). Therefore, Sunday – the Lord’s Day – begins at 12:00AM, not at any time on Saturday.
Note: Mass attendance on Saturday evening fulfills our Sunday obligation only because the Church makes a provision for this (ie. , 1248.1Code of Canon Law).