no confirmed date but seems likely to be starting tomorrow or Friday. 

My guess is right after the artifact enhancement event ends

sounds about right. :P

Surely they would never.

Any news on this?  It is typically on a weekend, but if they wait until next weekend the rotation is basically over.  

The Free Gear Weekend should be two weeks into the rotation.      

SoonTM

(I'd expect it to start before the weekend ends)

also to be clear: 

i

if the timing of whenever this event happens isn't enough indication, don't expect these to be smackdab in the middle of a rotation but rather sometime in the back half of one.

It is live.  Go rebuild it all!