Yes, hyphen; no 's'-- when it is an adjective.
No hyphen and add 's'-- when it is a noun.
A ten-minute coffee break; a 3-day binge.
The coffee break was ten minutes long; my binge lasted 3 days.
You will admittedly sometimes find the hyphen missing as in the movie,
The Seven Year Itch-- but who says screenwriters are literate?