If you are interested to try out the new Heroic modes for Fallen Protectors, Kor’kron Dark Shaman, and General Nazgrim, you will have a chance tomorrow.
Check here for the Raid testing schedule –> http://us.battle.net/wow/en/forum/topic/9754146011#1
Also, for more info about the PTR and testing check out the PTR forums here: http://us.battle.net/wow/en/forum/9344478/