#1 - Feb. 5, 2013, 9:58 p.m.
(Please do not use this thread to discuss other warlock or non-warlock related topics, including but not limited to, your pitch for a quest line for your class.)
To begin the Black Harvest questline on the PTR, you can find an item that starts the quest as a drop on the "Green Flame Infernal." When 5.2 goes live, the item will be rarer but not stupidly rare.
1) At one point you will be asked to speak with a Warlock trainer. The quest is not hooked up to every possible trainer, so keep talking to trainers until you find one.
2) At a later point in the quest, there is a timed element. In the current build, you must finish the trial within the time frame given or be forced to redo it. In a future build, you will be able to proceed even if you fail the time check. This will make sense when you see it.
EDIT: The Green Flame Infernal is just east of the Shado-Pan daily hub in Townlong Steppes.
EDIT: If you provide any difficulty feedback, please share the ilevel of the character you used.
EDIT: For Point 2 above, I was trying to be too non-spoilery. You may just want to ignore the loot and run to the end for now in order to make it before the timer expires. In a future build, you won't be able to pick up any more loot after the timer expires, but you won't fail.