By Siren.Enternius 2010-09-10 15:57:11
It's not 48 hours from the time you finish them, I don't think. I did one on the night of the beta release, and then the next day I could do them again, so maybe it's every other day at 12 JST or something like that.
But basically, yes, they have to be available to use before you can swap them out.