From http://us.battle.net/wow/en/blog/175...dule-1-14-2015
February 3, 2015:
Blackrock Foundry opens with Normal and Heroic difficulties available.
World boss Rukhmar becomes available in Spires of Arak.
February 10, 2015:
Mythic difficulty becomes available.
February 17, 2015:
Raid Finder Wing 1: Slagworks (Gruul, Oregorger, and The Blast Furnace) unlocks.
February 24, 2015:
Raid Finder Wing 2: The Black Forge (Hans’gar and Franzok, Flamebender Ka’graz, and Kromog ) unlocks.
March 10, 2015:
Raid Finder Wing 3: Iron Assembly (Beastlord Darmac, Operator Thogar, and The Iron Maidens) unlocks.
March 24, 2015:
Raid Finder Wing 4: Blackhand’s Crucible (Blackhand) unlocks.