[quote="TimothyH, post:1, topic:264560"]
When does the liturgical day start and end?
Do I pray the mystery of the rosary for Tuesday if I have stayed up past 11:59 PM on Monday, or do I pray monday's mystery. Or is it when one goes to to sleep and wakes up again?
What about the Liturgy of the Hours? Mass? Reception of the Eucharist?
(Yes, I realize that some of this has already been posted)
Most days begin/end at Midnight.
Sundays, solemnities, and major feasts of the Lord begin at the "time of First Vespers" which is 4 PM on the evening before and end at Midnight.
For private devotions like the rosary, the mysteries of the day are only a suggestion. One is free to choose any set of mysteries.
The Church has a table of precedence for liturgical days--this is in the general norms for the calendar and is printed on the opening pages of the Roman Missal. It's also in volume one of the 4-volume Liturgy of the Hours.
When it comes to choosing the Mass, the priest is bound to follow the calendar strictly. But one thing to keep in mind is that sometimes "substitutions" are possible. For example, on a weekday in Ordinal time, a priest might choose a votive Mass instead of the Mass of the day. The point though, is that whatever options are available depend on the liturgical day and hour--which is either midnight-to-midnight or evening-before.