Adverb
cuándo
when
"¿Cuándo fue la última vez que dormiste bien?"
When was the last time you slept well?
Write it
Write a sentence with cuándo in it, whatever's on your mind.
It doesn't have to be perfect
Short story
A three-sentence story with cuándo in it. New one every time.
Couldn't write one just now - try again in a moment.