I'm not positive, but I remember it started some time in the late 60's. Later it was sent to only those that wanted it as a seperate printing. They even had some neat decals. My oldest decal is 1969, so that puts it in that era. I guess the postage rates forced it back into the magazine, also Model Avaiation became more than a newsletter when Potomac Publications went belly up and that ended American Aircraft Modeler, which used to be American Modeler, which used to be Young Men, which used to be Hobbies For Young Men, which used to be Air Trails, which I think used to be FLying Aces.
Or did you already know all this trivia?