14 day pass worth it?

Hello!

I'm planning Japan Trip from 11-24 DEC. I'm wondering if the 14 day Japan Rail Pass is worth it.
Day 1 Nagoya to Osaka
Day 2-4 Osaka
Day 5-6 Kyoto
Day 7-8 Kanazawa
Day 8-9 Nagano
Day 9-12 Tokyo
Day 13-14 Nagoya

Also, if i purchase the pass on September 30, and exchange when I get to Japan mid Dec, is it still valid and not affected by the price increase recently announced?

Thank you!