Early visaapplication; missing airticket

Hi, I'd like to visit the People's Republic of China towards the end of September this year. Since I'll be travelling with the Transsiberian Train and therefore leaving Switzerland around August 15, I am wondering if I can get it already now. There are some other visas I'll have to get and time might get tight.
I also want to leave by train towards Vietnam and intend to buy the ticket in Beijing, and therefore won't be able to show a round-trip airticket. Can I somehow get around this requirement?
Thanks
Barbara