I pack my whites away after Labor Day plus anything linen. I just enjoy the change in seasons. I still wear some white in the winter like my white down jacket, but this is more snow bunny clothing.
I think this "labor day" restriction on white is ridiculous. I will wear whatever I want whenever, and if someone finds that offensive then that's their problem.
I just base my decision on the environment and the atmosphere. If it's sunny and bright, and I'm going to a picnic or cafe, or someplace with a tropical vibe, then I'll wear white all through september or even early october here in PA. Or, if I'm on vacation in CA or FL, anytime of year.
But, if it's cold and I'm wearing a wool coat or cashmere sweater, then I'll usually pick warmer fall colors...just because they go with the whole look. For example, I was in Scotland in July and it was only around 50 degrees some days -- so I wore warm clothes and ditched the light weight white skirts and sun dresses. I wouldn't wear a "summer" dress or skirt with a wool winter jacket.
But generally, I don't like "rules" of any sort -- I just say if it looks good, wear it!
it's up to you to wear white anytime. I personally try not to wear white after Labor day even though I live in South Florida because I love to dress up in early fall clothes. I just love the fall/winter season clothing!
I do wear white tops (shirts and sweaters) after Labor Day, but never bottoms, shoes or purses. Although "winter white" is acceptable to me December - March. That's only for me, though. I don't have an opinion on other people wearing it.