I use a Trello board to keep track of my fanfiction writing. Here's a simple overview of how I do it.
The first list, "In-Progress Fics", contains all of the fics I am presently working on and updating. For instance, as of right now, the 2 fics I am presently updating are "Infinite Possibilities" and "Elixirs and Potions", so those 2 fics have cards in the In-Progress Fics list
The second list, "Fic Ideas", is the fics I have yet to post/update. If I haven't posted the fic anywhere online, it goes in this list.
Each fic card in either of these 2 lists follows the format of the Weekly Fic Showcase on r/FanFiction, allowing for a quick copy/paste. More information is in these cards than would go into the post, but I can very easily copy the top of the card description and paste it into Reddit to showcase fic updates.
The other lists in the channel are per-fic lists of chapters. The due dates on the cards are when those chapters should be posted. The chapter can be finished before then (in which case I note it in the card description) but it will be posted on that date. The description is a basic outline of what should happen in that chapter.