of course like all good musician, his technique evolved and changed, his first two lps are quite diferent from penguin eggs.https://www.youtube.com/watch?v=hzo7fADr_50, annanwater that was recorded in 1970, and is lacking the percussive later style
the first recording which[i think] was demonstrating the percussive style was noahs arktrap 1977, sometime bteween 1970 and 1977 his style evolved
Wikipedis [which is not always the last word on everything] says
Another important feature was a regular percussive sound made by striking downwards with the middle and ring fingers of the right hand on damped bass strings close to or above the bridge of the guitar. This is akin to the technique used by banjo players called frailing. This can be heard to good effect on such Jones tracks as "Ten Thousand miles" (on The Noah's Ark Trap, 1977) and "Master Kilby" (on From the Devil to a Stranger, 1978). Jones also skilfully used selective string damping to achieve other percussive effects such as on "Billy Don't Weep For Me" (on From the Devil to a Stranger).