How much time should I allow myself to see/ explore SoHo, Little Italy, and China Town?

My mom and a few friends are all going to New York in a few weeks. We are all each choosing a day to do what we want and for my day I chose the above. There are also a few other things I want to maybe do later in the afternoon/evening (time depending). Any other tips/advice you have for me would be appreciated also. Maybe some good places to eat in that area or some must-sees and do's. Thanks :)