Our lil Mr. Oliver is 3 months old and we've had him for
7 days now.
He's definitely nipping among other doing other naughty things.
Among the mentioned techniques, my favorite is using the low/high tone "NO" and gently push my hand into his mouth as I hold him down. It seems to work (hit or miss) or atleast he softens his nibbles on my fingers at that moment. Also, I follow up by praise and offer his chew toy. Definitely frustrating, challenging and requires patience.
Wish us luck!