Its jumped around. Its typically on Friday but the first couple boxes were on Saturday morning IIRC and this last one dropped on the Thursday after Christmas.
Also, I didnt realize until a couple days ago that we have 2 boxes available right now as the Reindeer boxes are still there but on the last page, so both current boxes drop Archeum crystals, essence and regrade charms.
New RNG boxes are a bit postponed. May have negative effect if added right now.
Not added yet and may not be added for the next few days. We'll keep you all updated.