We were there last year when school started during the first week in August. Seemed strange to us because they had all sorts of going back to school shows on local tv.....our schools don't return until after Labor Day. But I know schools in the south return earlier.
The crowds were down, IMHO, but it was not uncrowded. It was not a mob scene by any means, just busy. DTD always seemed pretty crowded and Earl of Sandwich, in particular, was always busy. The parks did not seem bad to me....very hot, for sure, but not overwhelming crowds. There were still waits for popular rides and Fantasyland was packed because of the younger kids not returning to school. Nothing like mid-July, for example. The weekend was still pretty crowded.