Parallels seems to be the first ever to me, as well as the Mirror Universe or Lazarus' universe.I think what is interesting is we have seen plenty of alternate timelines in Trek. Many of them fixed at the end of the episode to restore the timeline but the Abrams movies was Trek's first ever divergent timeline in that time travel was used to create a new timeline that would not be erased at the end but instead continue on following it's own unique path. Thus it does bring in questions about time travel in Trek we aren't used to asking with the other time travel episodes and movies.