I'm totally in love with this whole idea by YANKO DESIGN
This is definitely my kind of calendar.
Especially for a countdown of sorts, it would be so fun for kids to do too. It reminds me of Christmas countdown calendars - loved those with the chocolates, then I found this:
by Dmitry Kutlayev from Russia link here.
But I found these calendar beauties on this web page - gotta give credit to where it goes - there are lots more calendar designs there!