Here is an example of how I wore winter white!
I find it very outdated when people say "no white after Labor Day". White is one of the basic colors that is a necessary one in every closet. It would be hard to completely eliminate it. That's why "winter white" term came in. Sometimes it is used to describe a color that's a little off-white, but other times it is just a way to justify wearing white after Labor Day.
I think if you find a piece that works with your fall or winter outfit and it is white, go for it! Embrace it and wear those whites confidently not matter what time it is. I think it is more important to focus on combining an outfit that is fitting based on weather, occasion, and season rather than worry about an outdated rule. Here is how I worked my white dress with fall colored accessories like the maroon hat and shoes.
Dress: Anthropologie old (similar here and here)
Shoes: old (similar here from Nine West)
Hat: old (similar here from J. Crew)