Travel Nepal-Guangzhou-Beijing-USA

I will travel from Kathmandu, Nepal, to Guangzhou for a 2hr 15min layover, then proceed to fly to Beijing. I will stay in Beijing for 4 days and then depart for the USA. Do I need to apply for a 24-hour transit upon arrival in Guangzhou, and then apply for a 144 hour twov upon arrival in Beijing? Or can I just apply for the 144 hour twov in Guangzhou? Thank you for your response.