JR Rail Pass start date

Hi there, i'm planning to get a 7 days JR Rail pass but due to it being an 8d/7n itinerary. Just wondering when would be the best time to start it ? Or shud i stay in tokyo for the first night without JR pass and start it the 2nd day when i start the travel to kanazawa?

Day 1 - Arrival then travel to Kanazawa
Day 2 - Day trip to Shirakawago and travel to Kyoto in the night
Day 3,4,5 - Kyoto and Nara. ( possibly Osaka if time allow it but whether is it better to spend more time exploring Kyoto than trying to cover Osaka for a day? )
Day 6 - Head back to Tokyo from Kyoto and spend d day exploring Tokyo.
Day 7 - Mt Fuji
Day 8 - Explore/shop, departure back in the evening.

Cheers for any advice

I would have it activated on day 1 with your trip to Kanazawa. Your day 8 is in Tokyo, I presume? If so, then you don't need the pass. Just use IC card or individual tickets.

...and I concur.
If you're leaving out of Narita, you can use the 1000 yen bus.
http://accessnarita.jp/en/home/
If out of Haneda, there are cheap subway and rail to Haneda combo tickets too.
http://www.jnto.go.jp/eng/arrange/transportation/discount/rail-
bus.html

I do hope you're aware though that there is no train to Shirakawago so you have to pay for the bus. For Mt Fuji, I presume you mean Hakone - you can go to Mishima Stn and get a Hakone Free Pass.
http://www.japan-guide.com/e/e2358_008.html
http://www.japan-guide.com/e/e5210.html
Osaka is better in the evening after the temples in Kyoto close around 5 PM.
https://www.youtube.com/playlist?list=PL7LcPcmoSg-jkgQdiQlK2bcKCzr2pJQ...
On another evening, you can also go see Kobe if you like.

You for to Odawara if visiting Hakone, as to purchase the Hakone free pass, you much buy it from a Odakyu Station. Mishimi is not.

But when the OP says mount Fuji, I'd assume Fuji 5 Lakes area. Use JR pass to get you as far as Otsuki Station, then purchase the 3350 free ticket that gets you unlimited Fujikyu Railway and local bus usage.