Funnily enough, there has been a slight (unintentional probably, but it's there all the same) pattern for the VA selections here. So far, it would be that 2 ponies would be done relatively close to each other with some sort of break afterwards (aside from Mayor Mare, but that was a relatively quick call as well);
Twilight ->
Applejack were very close, lasting through that month.
Pinkie pie ->
Rarity were kind of close as well, though there's a bigger gap there that is most likely attributed to a Bronycon Build/the holiday season. If patterns are anything, then this would mean that sometime mid June they would start up the Rainbow Dash audition. Still Though, it's hard to imagine that the Fluttershy audition took an entire month.
In terms of character reveals, if we take the first releases as AJ and Twilight as rough, then they kind of have a pattern as well. Mane 6 started development around late may, but let's just say they had the summer before the first livestream where 2 characters were shown off in rough form. Then it isn't until the end of that semester into the winter where the next 2 characters get shown off in rough form (technically Pinkie Pie and AJ were in trailers before streams). Given that another semester has passed, we can assume that there must be some rough form of either Rainbow Dash of Fluttershy, though I'd hesitate to say both are in rough form because they did say there will be some sort of flying/air mechanic for pegasi that might go through different revisions for characters much like Rarity getting a different projectile mechanic. I'd say it's a prime time for another stream.
I think the interesting bit about their lack of updates is how they haven't been doing trailers since Twilight's in
November, which was a little over a month after the first stream when characters still had a bunch of work ahead of them. I'd think they'd release at least one trailer after their last stream in february since they must have gotten work done on Pinkie Pie/Rarity since then. They really need to put in more updates regardless, no matter how small. I don't mind updates like
this or
this that just give a tiny glimpse at the animation versus something more detailed like showing off
game mechanics.