Jedi Bibliothek has discovered the titles of the first six episodes of season 3 and their airing dates.
03×01-02: “Steps into Shadow, Parts 1 & 2” – 09/24/2016
03×03: “The Holocrons of Fate” – 10/01/2016
03×04: “The Antilles Extraction” – 10/08/2016
03×05: “Hera’s Heroes” – 10/15/2016
03×06: “The Last Battle” – 10/22/2016
From the look of the third episode, it looks like season 3 will deal immediately with the Sith Holocron and Maul’s storyline and is probably the episode that features Ezra and Maul merging the Sith and Jedi holocrons together as seen in the trailer, the fourth episode is definitely the Wedge Antilles episode. My guess would be that the fifth will feature Cham’s return and the sixth episode could be the Mandalorians one, that would be my theory.
We also have the official synopsis of the season which clearly highlights that Ezra and Sabine will be focus this year:
Having established a secret base on Atollon, the Ghost crew, now led by a more powerful Ezra, strengthens the rebel fleet by acquiring new resources and recruits eager to stand against the Empire. However, the Imperial efforts to eliminate the rebellion are now being led by the coldly analytical Grand Admiral Thrawn, whose strategic, tactical and cultural insights make him a threat unlike any they have faced before. In season three, Ezra and Sabine take on new roles and challenges as the rebels prepare for their biggest mission yet—a direct assault on the Empire.