The Star Wars Rebels: Spark of Rebellion DVD is currently listed on Amazon for pre-order. The DVD includes the one-hour special written by executive producer Simon Kinberg, which was previously shown during San Diego Comic-Con weekend. The release date is October 14, 2014.
Given the date, there is a possibility that the one-hour special could air in September, while the rest of the series continues in October. This, however, is just speculation. The one-hour premiere of the series will air on the Disney channel and the series will continue on Disney XD. Stay tuned for more details as news develops!
(via Rebels Report)