#1 - July 1, 2018, 2:41 a.m.
First off here is that one you missed.
https://us.battle.net/forums/en/wow/topic/20767336972?page=2#post-30
Not the two additional follow up quests as well in Slithus which actually give the Heart of Azeroth neck piece right? Because the wording on the blue post which I've linked below almost indicates that you might get the Heart tomorrow. Specifically the part the talks about after the Battle for Lordaeron.
Link:
https://worldofwarcraft.com/en-gb/news/22010728#1