Well, on the island, when Juliet was dying at the start of the Season 6, her last words to Sawyer were about getting coffee and going dutch, which at the time seemed just like delirious rambling due to her injuries. It turned out she said these things later in the sideways world, just as she and Sawyer started to remember each other.
To me, this means that Juliet already had one foot in the sideways world as she was speaking her dying words to Sawyer in the real world.
Thank you for answering! Also, did they indicate that Ben had a full memory flashback?