Congenital blindness due to retinitis pigmentosa - does it exist?
I have only ever heard of one case where RP caused blindness in a newborn. Unfortunately, I am unable to release the name or any details of the patient because of privacy issues and so forth. 

Usually blindness from RP comes after a few years of life (as you said), making blindness from birth (or even early infancy) very rare. 

I can tell you, however, that the formerly stated patient suffered from type I Usher Syndrome, if I remember correctly. I apologize for my inability to provide you with more specific details on this.

I don't know how much this will help in your search, but I sincerely hope that it does.

CDB