The pitfalls of writing about a live series... · 3:27pm Jun 14th, 2014
My copy of The Journal of the Two Sisters is still in the post -- but according to someone who's already got the thing, it's explicitly stated that "Pinkie Pride" is Rainbow Dash's tenth birthiversary. It's probably impossible for me to reconcile the chronology of "Where They Understand You" with that, since I've been assuming that a) Rainbow is (just about) an adult by the time she moves to Ponyville, and that b) she's the last pre-Twilight Mane Sixer to settle there.
Meghan McCarthy has stated that she thinks of them as (roughly) early 20s now, in human terms. So if Rainbow was 21 when "Pinkie Pride" went out, she'd only have been 11 when she moved. Since we know that she was still in Cloudsdale when she got her cutie mark, and since I can't imagine her being much under 11 at that point, it implies that she didn't get anywhere near Cloudsdale High, or that she's actually much older than 21 now. Neither of which will work for me!
I feel an Alternate Universe tag coming on. The writer's equivalent of sticking your fingers in your ears and going, "La la la! I can't hear you!" ;)
The only stuff that is primary canon is the show. Secondary sources are always iffy.
The show's official chronology is screwy. For instance, trying to compress the first three seasons into one year doesn't work -- it contradicts the internal evidence from the episodes, which show enough springs, falls and winters that the first 3 seasons have to take almost four years (and that's if you switch the order of two close-sequence episodes to avoid having an extra year's gap in there).
Here's my chronology. Note that in it the age of the Mane Six at Luna's Return ranges from 17 (Twilight) through 22 (Applejack) and they are now 21 through 26.
Attempting the place the ages of the mane six in human terms is a fools errand in any case. Even before we take into account the Equestria Girls universe (where their paralell alternates are High Schoolers, whether seniors or sophomores is unclear) there is such a variation in their maturity level (on the one hand they all have jobs, homes and such, on the other they act as childishly as the target audience at times) that trying to nail it down is tricky to say the least. I think early 20s is too old, personally.