Blizzard has reached out to us at Wowhead and clarified that the first Spark of Shadowflame will actually be available the first week of Patch 10.1!
Previously, we reported from an interview that the first Spark of Shadowflame would be available the second week of Patch 10.1. However, Blizzard has now reached out to us clarifying that this is not the case, and the first Spark of Shadowflame will be available as soon as Patch 10.1 drops.