Aiming for late July but clearly they missed.
http://www.nintendoworldreport.com/news/43101/pokemon-go-plus-officially-delayed
With no shipments in sight and only a couple of days left to ship it, Nintendo has officially delayed the release of Pokémon Go Plus.
The Bluetooth Low Energy accessory was tabbed for a late July release at E3, but the various national Nintendo Twitter accounts announced around the time of Nintendo's financial report that the device would ship in September.
No reason was given for the delay. Currently, Pokémon Go has been downloaded over 75 million times.
Speaking of that, has anyone else had the glitch where Pokeballs just fall short every time? It seems like the screen input is lagging enough that it is physically impossible to make a stroke long and fast enough to hit the target. When that happens, I've learned to just give up before I use up all my nice balls in rage.I've had that happen before. It's frustrating. I actually found the most successful way to fix it is to force shut down the app and restart it.
Nintendo probably looked at the preorders, then looked at the manufacturing and said, "Oh, ****".