"You can't talk about fall stuff until at least September 22nd! No pumpkin spice before then"
Nah, I have a Better Barometer.
You can either use the start of the NFL Season (September 7th), the start of the Preseason (August 10th) or if you really wanna stick it to people, the Hall of Fame Game (August 3rd).
Christmas gets to creep into October, I see no reason why you can't start liking fall shit in August.