I think by the first real visit I knew--because Arthur actually got messy, a little bit. Which reminds me, earlier in the comments you mentioned that this story was kinda playing with the unlikeliness of the whole team working together again, but it seems like you were also playing with the fandom misconception of pristine perfect point man Arthur by having Cobb fal into that trap and having those times when Arthur is like that be the times when he's not real.