If I'm reading your header right, you're in Zone 8

If so, I think it might be too early for the fall crop
Although I did just plant some, but don't know yet whether they'll germinate in this heat

You should probably see Farmerdilla's advice from the link below

Which is:
"In Augusta ( Richmond County) I can set Broccoli and Cauliflower as October 15. I start plants outside in July. Shady spot with only dimpled morning sun. Not even a turnip will germinate here in the open until late August. For best results I like to get Broccoli cabbage and cauliflower set just past Labor Day. The October transplant of broccoli and cauliflower usually do Ok, but often don't head until January. I like them around Thanksgiving, which is also when I plant English peas. I start and set collards on the same schedule as broccoli and cauliflower, shooting maximum harvest for New Years. Every one has to have Collards for New years. Turnips, mustard, kale, rutabagas, I direct sow the last week of August and then at about three week intervals until October 15. I am growing Pak Choi this year on the same scheduled as the other transplanted brassicas. I don't recommend direct seeding of Cabbage, cauliflower, broccoli or any of the large brassicas which require spacing of more than 15 inches."

Here is a link that might be useful: Fall Vegetable Gardening