Green’s Dictionary of Slang

(orig. US) preparation, esp. an accumulation of favourable publicity designed to popularize a person, product etc.

1929		Hostetter & Beesley It’s a Racket! 220: build up—The ballyhoo or stage setting which precedes an event, or the committing of a crime, or racket.
1938		D. Runyon ‘What, No Butler?’ in Runyon on Broadway (1954) 393: One of the oldest build-ups of a doll in the world.
1949		Wodehouse Mating Season 33: I remember hearing the Rev. Aubrey give the late Sir Philip Sydney a big build-up.
1952		W.R. Burnett Little Men, Big World 94: Rudy’s going to get a big build-up now. The new underworld boss—same old newspaper stuff.
1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 55: It was bonzer of old Arch to give me that terrific build up.
1976		Cab Calloway Of Minnie the Moocher and Me 110: Ted Husing, the announcer, always gave us a big buildup.
1999		Observer Screen 4 July 7: The months of build-up are every bit as important.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 6: Cuz once I’ve hooked a live one into thinking he can take me for a ride, that’s when I nail him with the ‘build-up.’.