Your game is only indexed on itch.io when there is a file to download. If you publish it now, it will show as free (because you can't charge for a non-existent file) and there will be nothing to download - people will possibly look at the page but then move on and forget about it. If they search for a Christmas themed game, yours will not appear because it won't be indexed.
When you add a file in it, it probably won't appear under new releases any more and you will have missed that window of opportunity.
You should publish it as soon as possible, because people are starting to play Christmas games - but don't publish it until it is ready.