"Before his time" can either mean before he was born, he had vision and knowledge unusual for his era, or that he died too young, depending upon the context.
"He didn't know anything about the Beatles, they were before his time."
"Jules Verne was a writer before his time; he wrote about space travel long before we actually sent a man to the moon."
"Sorry to hear about Ben's car accident. Poor guy -he just graduated from university and had a great job lined up. He died before his time."
- For Teachers