How the JR pass counting?

Hi there,

My first time in Japan :)
Japan trip 6-15 Oct.
Can I use the 7 day JR pass for NRT airport to Tokyo on Oct 6 (Day 1) and go to Osaka in the next few days then go back to Tokyo on Oct 14?

Is the JR pass counted from the first day of activation and counted even though we didn't use the JR pass on that day at all, or only on the day that the pass was used?

Regard,
Ty