The earliest "BoCoCa" citations seem to be from about 2002. "BoCoCa" is not to be confused with "Rococo" art or a new form of "cocoa" or "cocaine."
http://www.villagevoice.com/issues/0239/goldstein.php
(September 23rd, 2002)
Front yards in Brooklyn? Whole blocks in bloom? Love 'em, water 'em as the yuppies in Carroll Gardens have for the past five years. The neighborhood's even been puffed by Vogue, and Smith Street is the heart of Brooklyn's très fabulous Bococa district.