I was in a similar situation a few years ago. If nothing has changed since then you will most likely be fine. Your best bet is to also contact your Chinese university about this, since they are the ones to handle crucial parts of this procedure.
Your X-visa will look something like this and have an issue data and an enter-before date. In principle you are good to enter China at any point between these dates, but you will also find a note clipped on the opposite page of your passport, reading
The holder of this visa is kindly reminded to go through the procedures for obtaining the residence permit for aliens in local public security bureau within 30 days of entry, to avoid illegal stay.
In order to get your residence permit you will need some documents from your university, and they might not be able to prepare them for you within the first days. In case that you risk running into the 30-day limit, at least my university was able to provide me with documents that allowed me to apply for a L-visa (travel) with zero entries allowed to bridge the time from entry + 30 days to application for the residence permit (you are good once you have applied, not issuance).