You can read about my trial (you can also try search older trials). Based on weather statistics I have even more challenging climate for okra, but I compensate it by using cloth for the whole season. I could do without if summer is really favourable, generally it’s needed so far. Had one plant grow without and by the end of the season it got to the same size as yours at mid july. But that trial did teach me that okra can also tolerate cold quite well. Those just refused to die even when temperatures didn’t really go over 20C during the whole of june. Those under cloth grew a little during june, but they also suffered. Hotter period in july saved them and I got seeds also. I would sow them as early as possible, some 10 days before it’s likely to be frost free. It might not make harvest any earlier, but it might help with the selection. In my main project I had clear plastic for the early season to help germination and early growth, but that small trial I sowed about 20 seeds under cloth when ground was still cold and 2 of those germinated about 10 days from sowing. Didn’t check what the ground temperature was, but air temperature got barely to 20C at most. The cloth makes it a couple degrees C warmer so I would think with black mulch around 20C over longer period should be enough.
I was wondering, why didn’t you pick those pods at the end of the video or where you just showing those that were ripest. Over here they never get that dry, but I collect everything that has been in the plant a little longer and dry them in a drier. They don’t need that long to be mature and only need to dry.