Using JR pass

Hi, I would like know if buying a JR pass will be worth for my itinerary. 7 days ot 14 days?

I will be visiting Japan Tokyo on the 8th July till 21st. My travel plan is:

10 days in Tokyo
4 days in Osaka, With 1 day trip to Kyoto and Nara
And return back to Tokyo
Flying out from Haneda.

Would you recommend to get a JR pass? If so, shall I take out only 7 day pass just before leaving Tokyo to Oaska?.

Thanks
Hari