You can get a mount when?
Blizzard posted a new PTR release over the weekend, and the patch notes to go along with it. There are several big changes in it, none bigger though than the following announcement:
Mounts at 30?! Yes, it's true: Apprentice Riding and mounts are now available at level 30. Training costs 35 gold.
You can find all the details in the PTR patch notes here.