In next week's preview for Supergirl (which is based off if Kara told Lena her secret earlier) we can see an October 2
? 2018 date of death on a headstone for Kara. The episodes Fallout and Man of Steel aired October 21st and 28th and featured Otis and Mercy releasing Kryptonite into the atmosphere, affecting Kara and requiring her to wear a suit created by Lena to help filter it out of her system. The implication is that she now didn't have the suit and did in fact die. Meaning Supergirl Season 4 does begin in late October (good call
@selfishmisery). I would move Ahimsa and Parasite Lost to November though.