As a student in 1959/60, I first programmed the TX-0 (one of a kind computer, the first with transistors and ferrite core memory made at MIT Lincoln Labs). That machine was the progenitor of DEC's PDP-1 which I got to play with as an MIT employee in 1961. They were 18 bit machines, also using 6-bit codes for characters. It made sense to use octal, i.e. 3 bit groupings. This code written was for an assembler. I knew the group of guys that hung around the PDP-1 and coined the term "hack". Many eventually became DEC employees.

As a student I got to use (actually submit card decks) for the IBM 709, a vacuum tube machine. The code in this case was written in Fortran II. My first job as an MIT employee was to re-design some equipment we had connected to the IBM 709 to work with the IBM 7090 which was a transistorized version of the IBM 709. These were 36-bit machines and again used 6 bit codes for characters. Again it made sense to use octal.

It wasn't until I started to work for IBM in 1965 on the IBM 360 (model 67) that I had to think in bytes and hexadecimal.

Anyway, this predates the cited nostalgia! :)