I haven't come across much on this in the research literature, but I'm willing to stick my neck out and assert that one thing that absolutely drives people in schools nuts are the number of last-minute changes from above. People are told that they will be teaching different subjects or grades days or hours before the school year begins, for example. I was hired by the school at which I worked two days before the start of the school year because the previous 6th grade teacher had just been moved across the hall to be a bilingual teacher.
This is far from the most egregious example, but the state just shuffled around an awful lot of administrators in Nashville. A month before the start of the school year is a lot better than a day, but the former principals have been hiring staff and otherwise preparing their schools for the fall for two months now.
Imagine Mr. Smith hiring a new teacher in June and then Mr. Jones being installed as the new principal in July. What if Mr. Jones doesn't like the new teacher or the new teacher doesn't like Mr. Jones? It's going to take at least a year to sort these kinds of things out, and many of them could have been avoided had the state simply acted two months earlier.