This revisits how events from the first season would have occurred if Jim had never found the amulet, especially those of Becoming: Part 1 (2016), which is the reason for the title.
When Jim returns to Arcadia before it all started, Toby's teeth have wider spaces and are more crooked than when they are when Jim returns to present day. This represents the progress in repair of Toby's braces in fixing his teeth.