I tend to be extremely happy and obsessed with stories I'm writing until I hit about 80% done (it seems to happen consistently at that point EVEN WHEN I DON'T KNOW HOW CLOSE TO DONE THEY ARE) and then I transition into the everything is terrible stage and need to be talked out of it. Then I finish it, quite like it, get beta feedback, post, and crash again into MY STORY IS TERRIBLE AND EVERYONE WILL HATE IT. I've learned to post immediately before going to bed or doing another activity which will take me firmly off my computer so I'm not just sat refreshing AO3 and stressing.

Generally the point where I finally start liking it again for good is after I've posted the NEXT story. (Actually I've been doing well right now where I post one in chapters at the same time as I'm already writing my next long-fic. Then I've been focused on the one I'm writing and it's taken the stress off the one I've been posting as that's already gone into the "prev story" box in my head!)