The guy im talking to (not my bf..yet) wants a child but, not me! help

I'm only 19 , he's 20 . I've always been told I'm mature for my age but still having a child now is not only my agenda , he totally loves kids he's a uncle to 3( 2 year olds ) & he wants Nothing more than to have his own. I'm a sophomore in college. He is not in school but does work. Me and him haven't been talking that long (about 2 months) I feel that he will be my boyfriend down the line but, I feel need to focus on myself before adding a child & bf in the mix. He is a good guy, and I can see a bright future for us but no kid just yet , I can't seem to find a way to tell him no but I have to do it soon. Help please & thank you ?