Transiting via Guangzhou, Baiyun Intl Aiport but don't have the visa for final destination on hand

I am transiting via Guangzhou Baiyun Intl Airport to Kathmandu, Nepal. I will only stay less than 24 hour in Guangzhou. I plan to get the entry permit of Nepal upon arrival on the destination. But the requirement says I need the entry permit for final destination to be eligible to enjoy the short stay in Guangzhou.