From Guuangzhou Weather(https://www.travelchinaguide.com/climate/guangzhou.htm), I get to know that autumn especially late September to early December is recommended as the best time to visit Guangzhou. However, you may visit guangzhou in Jan although it is a little bit cold.

You may make a fexible visiting schedule with shopping on your own, and I would like to advise you several Guangzhou attractions(https://www.travelchinaguide.com/attraction/guangdong/guangzhou/) like Yuexiu Park(https://www.travelchinaguide.com/attraction/guangdong/guangzhou/yuexiu.htm), Bright Filial Piety Temple(https://www.travelchinaguide.com/attraction/guangdong/guangzhou/bright_filial.htm) and Sun Yat-sen Memorial Hall(https://www.travelchinaguide.com/attraction/guangdong/guangzhou/sun.htm). For shopping, Shangxiajiu Road and Beijing Road are good choices.

Mr. Reb Tan
I'm a Chinese girl named Elvira(an translator) live in Guangzhou. The weather in Guangzhou is moderate right now. Guangzhou's winter only gets really cold when it rains, But we rare have rain in early January. You only need to put on 2 or 3 clothes here. Contact me if you come to China, I can be your guid.