When to plant brown top

Guys the father-n-law wants to plant two places with brown top millet for doves. Our season opens here in the south zone around the 15th of Sept. When would be the best time to plant it to get best results for the opening date?

I want to say its 90 days till maturity. Last year I planted mine 1st of June and it did great. I'm not an expert by no means so I will stay tuned and see what the pros say.