Early this morning I did the Advent Calendar. No pet appeared in My Creatures. I usually make a big deal about getting a plushie and giving attention to the newcomer.
I think the "Pet" from the 18th may actually have been a random limited Plushie (shop limited Urseal in my case - I remember seeing it and running off to put it on it's matching creature) and the French side of the board seems to confirm this though my fluency in french isn't the best