If you haven't written The Thing at all yet, I'd do a different exercise, first. Before writing the big, multi-volume Thing, come up with a much MUCH smaller thing set in that same world and see what that does for you. Put in some hard parameters like page-length (I don't know if this is a comic or novel) or a finish-by deadline, and see how long it takes. What you'll discover is no matter how much pre-prep you do, the second you start putting it down on paper your mind is going to wander. Plans are going to evolve, new avenues of exploration are going to open up. It's fun, but it can be a creature that's hard to keep in its cage, too. The bigger the story, the bigger that creature. Big creatures are hard to tame. If you can't tame it, you'll never get it to do what you want, and that's so annoying!
Giving yourself some small, hard parameters is going to force you to put on your Editor's Cap, which is crucial if you don't have someone else going over your work with you.
Polishing or not-polishing a work you haven't started yet is overthinking it. You gotta do the act first and see how it comes out. How long does it take you?* What clip can you comfortably work at? Can you do it habitually? Do you even like the act of doing it? That'll help you figure out what kind of buffer you need. Once you start posting Consistency is going to be your greatest ally in getting eyes on your work. Like, years of consistency.
*Time isn't just the act of doing it, either. It's always helpful to write, then let it sit, and then look it over with fresh eyes week(s) later. The longer the better, honestly. How do you account for that in your scheduling? You should make that work for you, too.
The smaller the story the better chance you'll have at Finishing it. Writing a story fully, from beginning to end, will be very illuminating for you. Maybe one of your side-characters goes to a shop. Something happens to said-character on the way or the way back. How interesting can you make that? Can you write it in a dozen pages? How fun can you make that for yourself?
I'll leave it there. See how fast this simple tip got away from me? Start small!!!
Now get to it! 