No one knows the exact date for sure when Online TurboTax will open for 2019 returns, since it has not yet been announced. Normally the rule of thumb is early December; i.e., the first week thereof. If I recall correctly, however, it launched a little bit early last year.
As for the desktop software (CD/download), it usually starts becoming available around mid-November, but the exact date is not known. TurboTax is taking pre-orders for desktop software now on their website.
