Suppose that you apply for a language program that lasts from 2018-03-10 to 2018-07-20. You are going to apply for the student visa (X2) to stay during the period.
However, I'm sure the legal stay does not start in 2018-03-10 and end in 2018-07-20. It is more like 2018-03-03 and 2018-07-27, or even longer period is allowed.
So after getting the visa, when can I start to enter in China and stay there? And until when must I leave China?
Or since the X2 visa is for people who study there within 180 days, can I decide any 180 days frame as far as it covers the language course?