6B mid missouri seeding time?

Planning a kbg/prg rennovation for the first time. Grass is all dead so plan is to dethatch and bag, core aeroate, soil treatment of humic acid/fulvic acid, drop seed, top dress low spots and slopes, then spray mestrinone and irrigate. Resources say ideal times are early September, so I planned months ago on September 8th, but then a heat wave hit so I pushed it back. It's starting to cool down to the 80s so I planned for September 15th, and looking at the weather every day, but now it's saying another small heatwave so it'll be 94 that day... what are you guys doing? What should I do? I don't want it to dry out or get sick but also don't want to miss the window