This should be done during the Monday morning (most ideal for people's schedules) or Monday evening SWAT on 20-June-2016. This is a follow on from T127250: Prepare Wikidata descriptions to roll out to stable.
In T127250: Prepare Wikidata descriptions to roll out to stable there will be an additional patch slated to land 17-June-2016 that, once merged and slated for train rollout 21-23 June, will add logic to MobileFrontend to ensure that if $mfUseWikibaseDescription is true, or if the user is on beta, then Wikidata descriptions will be shown.
The practical consequence of the timing of the patches is that Wikidata descriptions will not show on the beta mode of the prod cluster for 1-3 days, depending on whether a server is in group 0, 1, or 2, but then they'll be back on across the board after the train finishes rolling 23-June-2016.