PSA: unsurprisingly, promised dates change :)— Tommaso Checchi (@_tomcc) August 11, 2016
We said that Rift support would be in 0.15.6, but it will be out next week instead!
Keep in mind that, as Checchi himself states, scheduled release dates can change, so don't take the "next week" time frame as gospel. Microsoft first announced that Oculus Rift support would be added to Minecraft for Windows 10 back in March as a free update to the game. When the Rift support does launch, Minecraft will be available to download from the Oculus Store in addition to the Windows Store.