For the time being, I would say don’t actually watch at all. Wait till the season/series is over, which should be in four more eps. BECAUSE YOU WILL FALL IN LOVE AND–*ahem*. I’m super emotional over them. I’m going to be soooo wrecked if anything happens to them and because they’re not main characters and were introduced as villains and this is a scifi show with increasingly high stakes, I’m always worried about them. I’ve been waiting for two years for something to happen to one or both of them.
I…think you could start watching in season 3 and be MOSTLY all right. Delle Seyah actually shows up in the first season, she’s one of the ruling nobles in the area. Aneela as a figure is important earlier than season 3, in fact, her story is part of the show’s story from the start, in the little bits and pieces of Dutch’s past that slowly get revealed, but if you genuinely don’t care about Dutch, Johnny, and D’av, then she only really shows up in season 3.
I would say that watching the whole thing only enriches Delle Seyah/Aneela, despite not being main characters they’re so intertwined with the central story, but I also do very much love Dutch and Johnny (and to a lesser extent, D’av). Perhaps watch the first four episodes of the first season? The fourth ep is when Delle Seyah is introduced. If you find that you can tolerate the still rather episodic, introductory nature of those episodes, keep watching, otherwise, skip ahead?