Is it worth getting 7day plus separate ticket or 14day pass for this trip

Hi everyone,

our family of 4 adults is planning the following trips by JR this October:

8th Oct: Tokyo - Okayama
10th Oct: Okayama - Kyoto
14th Oct: Kyoto - Nara
17th Oct: Nara - Tokyo

We are wondering if buying a 14day pass is the most cost-efficient way to travel or should we buy a 7day pass and then separate one-way tickets either for the Tokyo - Okayama or Nara-Tokyo trip.

Also - if we choose the 7-day pass plus a separate one-way ticket, should we buy this online now or in Japan directly before travelling?

Please advise,

Thank you!

SJA