When Can You File For Child Support Orders

My name is jasmine and I am currently 6 months pregnant. I have not seen or talked to the father of my child since I was 3 months. I don't know why he just up and disappeared the way he did but I would like to file for child support against him. I've recently located him on face-book but I'm just completely over him and his games. I have tried too many times to give him chances to do right by me but now I'm done trying. I shouldn't have to do this by myself because I didn't make this baby by myself. I really just want him for him to be a part of his son's life. How do I go about filing for child support against him and what are my options????