My 9 month old cries violently when I say "No!" in a louder-than-usual and stern voice. This happens when she bites me while nursing. Is it too early to discipline her?

Our baby does the same, she bites my wife when latching too. So what my wife does is to unlatch the baby and stares at her telling that's not good in a low but serious tone. Reine is right, some babies find it funny if you're correcting them. My baby just smiles at my whenever she tells her "that's not right." I find it funny too haha, although it's really painful for mummies. :)