Can someone develop schitozophrenia in their 30's?

Schizophrenia: This disease, manifested by disruption of thought processes, usually begins at an early age, usually before 19 years old. It is unlikely, but not impossible, to develop it in your 30's. Of note, relatives may have missed the signs, which happen to be obvious late.

Yes: It is common to have the onset in late adolescence early adult hood uncommon after 40 or so.