Please correct my chinese "Today is my day"
今天是我的日子 is not something a Chinese person would say, because it is a direct translation of an English colloquial phrase. 

If you want to express your happiness on this day, you can say: 

光棍节真是为我设计的 (Single's Day was created for me). 

光棍节了真开心， 都来祝贺我啊~ (I am so happy that it is Single's Day. Everyone congratulate me). 

These are informal ways of talking, which may have better results if you want to make a joke :)