Was just playing around with the coverdatabase a bit and had a check on the average age of an original when it was covered. For the songs where I know the release year of both the original and the cover the age was 17.8 years. Not 19, surprisingly ;) Oldest one in the book was A Perfect Circle doing When the Levee Breaks. Done on eMOTIVe in 2004, it was 75 years after Memphis Minnie & Kansas Joe McCoy first released it.

On three occasions I have the cover listed in the same year as the original. First one's Bloodthorn covering ...And Oceans on the '... And Oceans vs. Bloodthorn - War Volume I' EP. Russian band Sultan did Metallica's No Leaf Clover on a tribute album. The third one... is a bit puzzling for me. Have listed Trampled Under Foot from Led Zeppelin as originally release on the Remasters Boxset in 1993.

Bit of searching and it's on Physical Graffiti from 1975. There's nothing like self correction, isn't there?