10 day trip - When should we activate the 7 day pass

Hello, we are arriving in NRT and travelling to Osaka and staying there for 3 days. Then heading to Tokyo and staying there for 7 days and will come back to NRT from Tokyo.

We are also doing some sight seeing in surrounding areas of Osaka and Tokyo during our stay there. Is getting the 7 day pass enough or should we consider getting the 14 day pass?

If we were to get the 7 day pass, is it smart to activate it on the 1st night? Or should we pay out of pocket to get from NRT to Osaka? When would be the best time to activate it?

Thank you!