It's common for children to be referred to as 小李, 小王, 小刘, etc. in Chinese (basically 小[姓], where [姓] is the family name).
I expect there is a certain age where it's no longer appropriate to call someone 小李, etc. I also guess it's more likely that 小李 (sounding kind of cute) remains suitable for females longer than for males.
Question: At what age is it inappropriate to call people 小李, 小王, 小刘, etc.? And is it different for males and females?