Should I take transit visa

Hi, I am Nepalese passport holder. I am going to fly from Vancouver to Kathmandu via China Eastern Airlines. I have two transit in China, first one is in Nanjing and other is in Kunming. My schedule flight time from Vancouver is 11:00 am and arrival in Nanjing is next day at 2:30 pm. I don't know my airport hours and flight duration from Nanjing to Kunming. But my departure time from Kunming to Kathmandu is next day at 2:15 pm. Should I take China visa before flying from Vancouver? Thank you.