Green’s Dictionary of Slang

(orig. US) to act in a self-important manner; thus big-timing n.

1947		(con. 1944) J.H. Burns Gallery (1948) 22: We kept on our MP brassards, and bigtimed it through Casablanca.
1957		C. Himes Imabelle 53: That was the way jokers in Harlem carried their money when they wanted to big-time.
1965		C. Himes Rage in Harlem (1969) 54: [as 1957].
1979		E. Torres After Hours 114: [T]he big glamor days are over. Carlito Brigante ain’t big-timin’ anymore.
1988		D. Woodrell Muscle for the Wing 31: Big-timing her out of her hip huggers before they even left the parking lot.
1997		N. Barlay Curvy Lovebox 77: Nood’s [...] smug with himelf an’ his big-timin’.
2018		J.-P. Jordan Joys of War 112: I don’t big-time it. I don’t have to. Those who are arrogant think they are good; those who are assured know they are good .