Supposedly Jimmy Webb and Linda's cousin Susan Ronstadt broke up and that inspired Jimmy to compose "By the Time I Get To Phoenix". According to Wikipedia the first record he purchased was a Glen Campbell release. Jimmy wrote more hits than anyone to further Glen's career.
"By the Time I Get To Phoenix" was first recorded in 1965 by Johnny Rivers (Ramistella) and is on the album "Changes" that was released the next year.
The Glen Campbell cover from the 1967 album of the same name won Grammys, got well into the top thirty and the number two position on the Country chart.