Complex sentence: This would grow to fruition when Dylan began work on his next album, "The Freewheelin'Bob Dylan", a year later, by which time both Dylan's reputation and his stockpile of original compositions had grown considerably.
Split into simpler sentences: This would grow to fruition when Dylan began work on his next album, "The Freewheelin'Bob Dylan", a year later. By then, both Dylan's reputation and his stockpile of original compositions would have grown considerably.