What did a German minister say?
First they came for the communists,
and I didn't speak out because I wasn't a communist.
Then they came for the trade unionists,
and I didn't speak out because I wasn't a trade unionist.
Then they came for the Jews,
and I didn't speak out because I wasn't a Jew.
Then they came for me
and there was no one left to speak out for me.
Pastor Martin Niemöller (1892–1984) is the man to whom those lines are attributed. They are "about the inactivity of German intellectuals following the Nazi rise to power and the purging of their chosen targets, group after group." He spoke against Nazism, was sent to concentration camps, survived, and lived as a pacifist leader into his 80s and the '80s.
When is it time? The time to speak out against killing our fellow humans is always and forever now. If you know an intellectual who is not using that authoritative platform--that is, credentialed knowledge--to speak out for nonviolence, ask 'why?' It's time.