I would say for now, list it in the chronology in the order you are posting, until it is finished. The reason I say that is, another author had a similar many chapter fic that she wrote as you are, starting with a piece that ended up roughly in the middle, and higgledy-piggeldy after that. Readers who were following along as she wrote it were happy to read it that way, and could certainly follow the unfolding of the story and the way the author's thinking evoked evolution of the characterizations, especially the main OC, along the way. When she posted a story-chronological listing later, if you read it that way it didn't quite hang together. Some of the things that were written earlier honestly needed a little tweaking to keep the characterization and continuity together. As far as I know, she never went back and fixed it, and so it remains a bit jarring.

Another long long piece written the same way was tremendous fun, and suffered from exactly the same problem. So the authors took down the whole thing, and started over again from the now-recognized beginning, changing and tweaking and reposting episodes that were sometimes significantly different now that it had all come together. But they never finished it. They lost the muse, or the friendship, or something, and now there is a 1/3 story posted, and the earlier work is gone. I still wish that someday it will be finished, but I don't hope for it.

So my thought is post it as it has come to you, enjoy the ride, and worry about chronology later. Or, use a short header at the beginning of each episode of the story to let people know roughly where it falls in the timeline.