In cookie making, Does creaming time change with the amount of butter used?
Yes, larger amounts will take longer to cream than smaller, how much time that really means depends on how you are creaming it. If you are using an electric mixer of some kind then I would expect the difference in time between 40 grams of butter and 80 to be pretty small as 40 grams or even 80 grams of butter isn't much. 

I wouldn't use time as a guide to creaming butter and sugar, the times given in recipes are guidelines and vary depending on conditions and equipment. Butter and sugar are creamed properly when the mix gets pale and fluffs up, expanding to nearly double its size, this may take more or less than 2 minutes.