Traveling to Beijing from Japan, staying for two days and then going Taiwan.

Hi,

I will be going to Beijing from Japan, staying for two days and then I will fly to Taiwan. I am from Sweden, so I should qualify for this 144 hours visa, however for the application process once I have landed in Beijing, how can I show them my tickets to Taiwan with confirmed seats? Usually you can only check in and get your tickets on the day you fly right? Or is it enough if I print out and show them the itinerary / e-recipt? Thank you