I am not an expert but I think I might have to measure the quanity before I chop or dice. My reasoning is if I were to chop up and then measure the quanity may be too much for the recipe and may affect the outcome.
I am not expert when it comes to cooking but my mom used to command me to cut all the ingredients in her recipe. She always tell me how many vegetables to cut, how big meat I will going to cut,something like that so that there is no excess after preparing this. You should measure the quantity before you will cut, and prepare the dish.
You mean you are supposed to measure the ingredients? Now I understand why my Indian-curry Irish stewed kangaroo spaghetti comes out differently every time.