Complex sentence: On August 17,2007, Ross announced that the album would be releasing on November 11,2007, then announced that the album would be released on December 18,2007, before being pushed back to February 19,2008.
Split into simpler sentences: On August 17,2007, Ross announced that the album would be releasing on November 11,2007. It was then announced that the album would be released on December 18,2007, before being pushed back to February 19,2008.