My grandmother was schizophrenic, and I worked in a 26 bed psych ward for 3 years.

Just be supportive of your friend. They will likely require daily medication as it continues to progress, and hopefully will stay on it as necessary. But if you notice any sign of extreme changes in their behavior, be sure to let someone know. Sometimes they may need help and guidance to get back on track, depending on the severity of the schizophrenia.

Also, be understanding... Don’t ask questions or pry unless they’re ready to talk about the diagnosis and bring it up to you. Just be a good friend like I’m sure you have been and let them know you’re there and non judgmental.