Board Thread:Administrative Requests/@comment-24573226-20160611000951/@comment-410526-20160612034152

I don't think there's enough evidence to say when the seasons started, except that Volume 3 definitely takes place in fall (with the last episode in winter).

This is totally speculation-y and shouldn't go in the timeline, but my impression was that the trailers were in winter/spring, Volume 1 was in spring, Volume 2 in summer/fall and Volume 3 in fall/winter.