The initial idioms of the letter N

nothing upstairs	Nothing ventured, nothing gained
nothing	notice
notify	notify about
notify of	not-invented-here syndrome
notion	not
nourish	nourish a serpent in (one's) bosom
nourish a snake in (one's) bosom	nourish a viper in (one's) bosom
the nouveau riche	now, now
now, where was I	now (that) you mention it
now and	now and again
now and then	now generation
Now hear this!	Now I've seen everything!
now or never	now or never, it's
now that	now then
Now what?	Now you’re talking!