Believe it or not, there are already diagnosed cases of flu in DFW. This is what the Center for Disease Control recommends for the timing of flu vaccines:
"You should get a flu vaccine before flu begins spreading in your community. It takes about two weeks after vaccination for antibodies that protect against flu to develop in the body. CDC recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout the flu season, even into January or later."
Resources for the 2019-2020 flu season: