I usually wear it just for my birthday. I'm quite happy celebrating my unbirthday ever other day of the year!
This year I will be at The World for my birthday. It is actually a trip planned by a friend of mine becasue her birthday is two weeks later and she can't be at WDW then (the dangers of having a birthday around a major holiday). We will both be wearing buttons at least on my birthday. I guess I'll follow her lead for the rest of the time, if she wears it or not.
I think you guys just solved a little potential jealousy issue I was afraid of.
We are going the day after my older dd turns 9. Younger dd won't be 6 for another 3 mos so I told her that Older DD will get to have Happy Birthday sung to her there, but not younger.
Maybe I will have older DD celebrate her bday the first day in Disney and younger DD get to wear the pin the last day of our trip. That should be ok. Now, to convince dh...
I don't think we have ever been on the exact DAY of the kids birthdays so they usually wear them the entire trip. We have always gone like a week before or after. My younger daughter was at Universal on her exact birthday but since they don't even HAVE a button she wore a button that we got at hallmark there but I don't think it is a big deal really. It is just a fun thing to do and it really doesn't matter. We also celebrated our anniversary while there on our last trip and even though it was a week later we wore our pins the entire stay.