Visa: if I need to provide a return flight date?

Hi,

I am moving to China (Shanghai) on July 30th 2018, and have employment with an International School, who will be arranging/processing my work visa on this date.

However, I would like to visit China (Shanghai) a few weeks before this date, as a tourist, with my wife, and so will need to apply for a tourist via.

Please could you tell me if I need to provide a return flight date to where i original flew from outside of China? Or can I just book a one way flight to China? I will obviously be staying in China and not be leaving China until much later on in the year (December/Christmas).

Thanks for your help in advance.