This is the way I did it...
A time (or I time) = PIC (even in the bunk)
Any other time at the controls = SIC
Any flight time before I was rated in an aircraft (I used my initial 3710 instrument check after winging and any initial check ride after that)= dual received
When I had a question about it, I usually went conservative. It is a lot easier to explain why you didn't log time that you deserve rather than why you did log time you didn't.
The Air Force guys have a very different way of explaining it.