I realized why they're waiting to release Teacher.
First of all with Good Thing they already have a potential summer smash, and with it impacting Pop radio on June 16th. They want to give it time to shine.
Second, they're probably waiting to send it to Radio on July so he's done with Kingdom and free to promote + it'll give it a month to grow on Radio so he can perform at the TCA and/or VMAs (hopefully both). I mean, the timing makes sense