Responses
the first chapters are from the future, after Jian Yi had returned from his absence when he was kidnapped ( http://www.mangago.zone/read-manga/19_days/bt/311115/Ch45/1/ ).
Zhan Zheng Xi is a college student now and he is living alone. Jian Yi is still at school because he lost two years ( http://www.mangago.zone/read-manga/19_days/bt/311118/Ch48/1/ )
the timeline of the chapters isn't linear :)
the chronology I've read
http://berry-muffin.tumblr.com/post/129355537030/timeline-19-days

this was first or this
http://www.mangago.zone/read-manga/19_days/bt/d410379cc11511b8/Ch140/pg-7/ from thear kiss?????...