Who should apply for the visa?

My son is currently in Nanjing on a study X for one semester. He would like to stay thru the summer after coming home for a brief visit in June. Should I help him apply for the tourist L here in the USA or should he apply while in China? I have already booked his flight back as I thought he was going to take another semester of school but he is unsure if that is going to happen, but would I have to also have his flight back before applying for the tourist L?