that's a great idea, but organising a place-like equivalent on the fediverse is probably low down on the priority list and requires a lot of work to implement.
I was more meant to create our own yearly event where we create a central "lemmyplace" instance; rather than a decentralized version, which given the data iops required, would probably not be feasible or desirable.
Hehe, when you run your own instance, you get certain freedoms, that might let you update the DB directly. I saw another user that set their date to their DOB, but I just set mine to my Reddit cakeday.