We celebrate "move-in day" with our teen - so far it is monthly (she is the one tracking it) and an excuse to have cake for dessert!
Monthly? That's funny.
I've been thinking a lot about this question as well and trying to decide whether we should celebrate "Homecoming Day" or "Adoption Day" or both. It seems kind of "excessive" to celebrate both of them and a birthday. By the time I have 9 kids or so :), I won't be able to remember all of those dates. Baby Girl came in Oct and was adopted in Oct so that would be two celebrations in one months. We just got done doing a birthday marathon (one in July, one in Aug) and so I'm not sure that I want to do that again.
What do you all do for your special days?