Green’s Dictionary of Slang

(orig. US) to occupy oneself with minor business, usu. in a criminal context.

1975		E. Torres Carlito’s Way 24: We was small-timing in them days — thievery, nickel bags and strong arm.
1999		J. Ridley Love Is a Racket 257: I didn’t have a head for small-timing my way through life any more.