I cancel it as soon as they charged my card. You still get the full month.
If you cancel your All Access subscription when you get charged, you've just paid for something you're not actually going to be getting the following month because CBS doesn't bill its All Access customers until the end of a given month... which means this idea makes no sense.
Presumably, it will have a bigger budget than CW shows, but hopefully, take place in the same universe. With Arrow ending and Crisis looming, I would absolutely love it if when the dust settles, Diggle is John Stewart, has his ring, and is one of the leads of this show.
The chances of this being set in the Arrowverse are completely non-existent.