I think you need to watch the commercial more carefully and check the local listings. The commercial, which I saw this morning, says the new Sunday lineup starts October 3rd, which is accurate. However it also says during the commercial "Starting September 27 This is the place for Kids." My local This feed (KWWT 30.4) happens to use the New York City This feed. The commercial may sound confusing, but it does say the new lineup starts next Monday, September 27, while the new Sunday lineup starts October 3. Ironically they show the Saturday lineup on the commercial, but they don't mention the date for it.
To clarify things if your This TV affiliate uses the national This TV feed, then they have no choice but to start the new lineup on September 27.
Also, the commercial does confirm a name change for the lineup. It will no longer be Cookie Jar Toons. Officially the kids block will now be called "This Kids." They have the smaller words "Is For" next to the This logo and above the word Kids which is underneath this.