PiC can sit where (s) he likes
Except during Take Off and Landing when they must ensure a pilot is
at the controls - as only one pilot possible (in single pilot operations)
that means the PIC must be at the controls for these phases of flight.
At other times they could even be in the back seat whist their
passengers fly the plane.
Sitting in L seat or R seat is similar to driving a L hand vs a R hand
car with, perhaps, the different perspectives being more important in
aircraft. Additionally usually only one (usually left) seat has a full
set of instruments "easily" visible - something else to get used to if
flying from the other seat the first few times.
I would say from a good airmanship viewpoint make quite sure
before flight that you both understand who will be captain when
and take care not to tramp over each other. But, again that
is good practice, not law.
From a good airmanship viewpoint understand that the switch may not
occur as planned - nor, even, as you wished:
Remember what "
In Command" means as PIC.
eg A Flight is planned A to C, via B where PIC is due to change over.
At B the original PIC is perfectly entitled, if they wish, to say that they
are remaining as PIC and the original passenger cannot insist on
anything - they are a passenger and must obey the lawful commands
of the PIC.
Conversely a PIC cannot just decide that they no longer want to be.
They can only hand over command to a qualified person who is willing
to accept the responsibility.
eg With weather deteriorating the Pax may decline the offer to become
PIC, and the original PIC must be prepared to continue the flight.
For this reason I think it is wrong, and probably illegal, for a PIC to plan,
or continue, a flight in to possible conditions (Wx, Night, etc) for which
they are not qualified but their Pax is. There is no guarantee that the Pax
would be able and willing to become PIC when required - and the Pax has
no responsibility whatsoever to ensure that they are.
The above are legality considerations, generally any splitting of PIC time
goes without a hitch - but my personal preference is to change over PIC
on the ground.