Well I’ve been a Rasta from ever since.

from Bob Marley – New Zealand Interview 1979 on Rap Genius

Meaning

There’s loads in this statement.

Rastafari is a religion heavily based on the ideas of Christianity.

Within Christianity, there is the belief that one must be born again to be saved.

The phrase “ever since”, means essentially from birth.

He could mean one of two things (or both):

  1. He was a Rasta since he was literally born.
  2. He was a Rasta since his decision to convert. (being born again)

In Bob’s own words:
http://www.youtube.com/watch?v=c6Ae-Q_GTaM&feature=player_detailpage#t=248s

To help improve the meaning of these lyrics, visit “New Zealand Interview 1979” by Bob Marley and leave a comment on the lyrics box