The correct answer to this question would be "it's ready when it's ready." Unfortunately, AT&T cannot promise a specific date because unexpected bugs can be found and Samsung would have to make a completely new build for testing. It would be released when everything is satisfactory.
Remember that every carrier model is different, requiring different software, so because T-Mobile or Verizon for example have their updates released, doesn't mean the same bugs will present itself in ATT's model.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.