You can purchase Stocking Packs during the pre-sale, December 1st - December 7th. Starting December 7th, make sure your stockings are hung to begin receiving your exclusive NC item prizes. You can also purchase special new Prize Claim Tickets starting December 7th. The event will run from December 1st-January 3rd, and prizes will be given out December 8th - January 1st. The Community bonus prize and 25-day streak prize will be given out on January 1st.
Edit: Date change! The 25-day streak bonus prize was to be awarded on 1/4/24, but now it be awarded on 1/1/24. Lucky you!