I was wondering the same thing earlier today. I'm hoping that we'll be given a slightly more narrow time frame in another few days. (If we're told several days in advance that it will be either this day or that day, that's fine, too.)
As of a few days ago (the last time I closely looked), I was at about 46 bottled winters. I have enough spirits saved up to buy the rest of the bottled winters that I need to get the blue fungi mount, but I'd rather wait until the last minute to actually BUY it. Any spirits that I don't have to spend on those bottled winters are being used to buy other outfit pieces from the new white winter gnogpack. I have the antlers & tunic so far. Every day's spirits and joys earned from daily quests are bringing me closer to completed outfits, so every day counts.