I think that set of dolls was always supposed to be released in 2013, including the Headmistress.
mattel has been good about showing a few dolls from assortments up to a year away with this line, but they tend to not show all the dolls for them. Now some dolls do get a preview closer to their launch though. But for the most part they are showing off stuff that can be up to a year away to keep interest going strong in the line over time.

