When you want a title to appear on the screen (i.e. “Two days later” or “September 1987”) how do you write it exactly?
— A. B.
Printing words on screen works much just the way you’d think. You write TITLE OVER, like this:
INT. JOHNSON FARM – DAY
Robin pulls open the curtains, so tattered they begin to rip from the rod. Bright light floods into the dusty room.
21 HOURS AFTER ABDUCTION
With a trained eye, she surveys the dank livingroom. Her attention focuses on a chest of drawers, which has been pulled out slightly from the wall.
Note that many times, you simply want to provide clarifying information to the reader, and have no intention of showing an on-screen title. In these cases, it’s completely acceptable to append the info to the end of a scene header.
EXT. POLISH GETTO – DAY 
INT. MARGE’S KITCHEN – NIGHT [WINTER]
EXT. CENTRAL PARK – [THE NEXT] DAY
Of course, only append this bracketed information if it really is crucial to helping the reader understand the scene — for instance, if your story moves back and forth between two timelines. Otherwise, you’re just adding clutter.