GOT it!
(I edited Mnemosyne post to save myself some typing

)
* Collected every day, and I watched all animations all the way through before collecting.
* Inventory full of different snowballs, junk items and few advent items
* I gave out a lot of items around Christmas
* Lots of Snowager visits
* Few Taelia quests - one yesterday
* I have at least one of all the items in my SDB, I used all items we got in a way they could be used (toys played with, books read + doubles bought for SDB, battle items equipped).
* I tried out every snowball theory that appeared (gave them, sent them, traded them, sold them...)
* I put up the Christmas Acara shopkeeper because I came here before collecting
* Had the same active avatar all month - nerkmid aisha
* Pet delighted
* I fed my pet two snow toasts prior to going for the calendar to make him bloated
* No Christmas or snow pets or petpets.
* I bought lots of scratch cards and scratched almost daily this month.
* I bought items from Terror Mountain shops - some sold, some fed to my pet
* had 4-5 advent items in my inventory + one advent items from last year and a couple of items from shops on terror mountain (in shop, inventory and SDB)