19. When do you think Wei Wuxian and Lan Wangji get together?
Pretty much as soon as the final credits roll...
given the final minute before said roll is... this :)
It's really more a question of how much time lapsed between
the end of the whole Guanyin temple denoument/disaster and that final minute on the cliff and boy, have the makers made it hard to work this out. They're leaving together! No they aren't. They are romantically back together by a Cloud Recesses waterfall! No, that's just temporary, they part ways on a cliff! Yes, and then... how long is it before they have had enough and are back on the cliff and those final credits roll?
Canonically, your guess is as good as mine. Has to be at least more than a day, since Wei Wuxian is - I think - wearing a different outfit. But I like to think it doesn't take that long for minds to catch up with hearts there.