Unix arrived at Princeton in the early 1970's and it might have been the third or fourth edition. The first time I heard about Unix was from one of my graduate students who was just starting work on his thesis, so it must have been before 1974. (He got his degree in May 1975 and this the only date I am sure about ;-)...)
Princeton is geographically close to Murray Hill (30 miles or so) and there was a lot of interaction between the two. I left Princeton in 1980 to join 1127 and another Princeton colleague had moved a year earlier.
Theo Pavlidis