Unfortunately, I haven't found early citations.
29 November 1979, Washington (DC) Post, "Anne's Reader Exchange," pg. E23:
13 May 1998, New York (NY) Times, "Look to the Cookie: An Ode in Black and White" by William Grimes, pg. F1:
The black-and-white has been around forever. Herb Glaser, the baker at Glaser Bake Shop on First Avenue near 87th Street, said that as far as he knew, Glaser's has been making them ever since it opened 96 years ago. "When I was growing up, I'd have two of them for dessert every day," Mr Glaser said. "I was a fat kid."
Technically, the black-and-white is not a cookie but a drop cake. The batter resembles the batter for a cupcake, with a little extra flour so that the dough does not run all over the place when it is dropped, dollop by dollop, on the baking cheet. "The trick is to add enough flour so the batter holds a shape, but not so much that the cookie becomes dry, which is a common problem with the black-and-white," Mr. Glaser said. Once baked, it is iced with chocolate and vanilla fondant frosting.
4 August 1999, New York (NY) Times, pg. F2:
What's Black and White and New York as Seinfeld?
by Florence Fabricant
28 January 2001, New York (NY) Times, "Smart Cookies: Why black-and-whites have assumed deep cultural significance" by Molly O'Neill, pg. SM39:
The black-and-white, that frumpy and oversize mainstay of New York City bakeries and delis, has not endured by dint of its taste. Unlike other edible icons, like New York cheesecake or bagels, there is no such thing as a delicious black-and-white cookied. They are either edible or inedible. Fresh-baked and home-baked are the best.
(Pg. 50 -- ed.)
Outside New York, cookies with black-and-white icing are cookies with black-and-white icing. In Boston, where they are called half-moons, and in the Midwest, where they are known as harlequins, they are considered ordinary and have been around, say most bakers, "forever."