Hi there, Bridget!
While no formal completion schedule has been provided to the public, Cast Members were able to provide me with some helpful (and consistent) information about the Fantasyland Expansion. The new area is set to open in two phases.
There are, as you point out, two jumbo-sized Dumbo spinners in the new area. The plan is to break them up, one opening in each phase: one of them is slated to open in 2012, the other in 2013.
According to Cast Members, in early 2012, the current Dumbo ride will move into take up position next to its twin in the new Storybook Circus area.
Storybook Circus and Dumbo will be first of the new Fantasyland areas to open in 2012.
Without a public schedule, however, it is difficult for anyone to know what, exactly, "early 2012" means. Your best bet is to keep an eye on the
Disney Parks Blog, which is your best source for official, up-to-date information about all things Park-related -- including the FLE. Do feel free to
contact me as your visit draws close; I'll be glad to try to uncover more (and hopefully more telling!) details for you soon.
See you later, celebrator!
-Deborah B.