Yes, those ripening dates are for California.
The Dong/Winter from Chinese Red Date is not the same as Winter Delight. Shengrui has been asked that question both here and in the FB jujube group and her answer both times is “no”. She is not familiar with the Winter Delight originally sold by OGW.
There are many Chinese jujube cultivar names that contain a reference to “winter”.
The Winter Delight sold by JF&E sounds like Autumn Beauty. There is only one early ripening large jujube in the US that I am aware of, and it’s Autumn Beauty.
It’s very easy to separate these two jujube cultivars if you’re growing both of them because no matter where you are, one is going to be early or even very early, while the other will be late or very late. Their fruit ripening times do not overlap even remotely. There will always be ripening differences in different climates and both AB and WD have some variability in shape and size, but they are still different enough with respect to both ripening and shape that they should be easy to distinguish if grown together.