It’s good form to put either “Day” or “Night” in a slug.
Some people may say “Avoid descriptors like ‘Morning,’ Dusk’ or ‘Three Strokes After Midnight'” but the Formatting Police won’t come after you if you do.
But what about “Continuous” vs. “Later”?
Let’s Look at Election:
“Continuous” should be used when one scene immediately follows another without any jump in time (as in a character is moving from room to room).
For instance, in Alexander Payne’s black comedy Election, Tracy Flick is driving away from the school, trying to dispose of the evidence of the trashed posters.
See how the action is, well, continuous?
Let’s Look at Shawshank Redemption:
“Later” should be used when there’s a gap in time. Here, there’s a considerable passage of time between Andy receiving the poster and it hanging on the wall.
We don’t know how much time has passed, but we can assume it’s been at least a few hours (unlike in the Election example).