Green’s Dictionary of Slang

(US black) unpunctuality.

1926		Van Vechten Nigger Heaven 98: I don’t know whether we should wait for Dr. Lancaster. Perhaps he’s keeping C.P.T.
1931		N. Van Patten ‘Vocab. of the Amer. Negro’ in AS VII:1 27: C.P.T. V. n. Coloured peoples’ time. Late.
1934		Z.N. Hurston Jonah’s Gourd Vine (1995) 70: He tole me he wuz crazy tuh marry Haley. He jus’ keepin’ colored folks time.
1967		J. Horton ‘Time and cool people’ in Trans-action 4 10/2: Middle-class Negroes who must deal with the organization and coordination of activities in church and elsewhere will jokingly and critically refer to a lack of standard time sense when they say that Mr. Jones arrived ‘CPT’ (colored people’s time).
1983		Eble Campus Sl. Nov.
1992		R.C. Cruz Straight Outta Compton 71: A fine cigarette woman selling Kool on colored people’s time tip-toed into the corner of the room and laughed.
2003		N.Y. Beacon 15 Oct. 🌐 Black Americans have sulked in their feelings of oppression and passively acted out their aggression in something called ‘Colored People’s Time.’ [...] a concept coined to label Black Americans’ habitual lateness.
2004		Boondocks 2 Nov. [synd. comic strip] huey: I dreamt I talked to God last night [...] He said, Don’t worry about the election ’cause everything would work itself out soon. [...] Of course, to God, ‘Soon’ could be, like, 50 million years. caesar: Yeah, He’s been on C.P. time lately.