I do think it starts way too early... but the alternative is them booking more nights in September/October to consolidate the event closer, reducing park hours for regular guests during those months even further.
HHN/Halloween is my favorite holiday, but anything before memorial weekend to me is just too much. Seeing pumpkins last year in Main Street mid-July is just jarring.
I think a fair solution is if Disney can figure out a way to increase capacity at the parties, while reducing the need for so many nights.