Is it okay to decide to eat breakfast at 9 so that i wouldn't need to have my lunch at 12?

This is like asking if I fill up my car with gas at 9am will I need gas at 12noon? There are way too many variables to answer this question. Your body needs fuel for physical and mental activities. The quality and quantity of the food matters as well. Also recognize that carbs tend to last as a fuel source for only 60-90 minutes while protein can last for up to 8hrs. Hope this helps to clarify.