Use this phrase to talk about something that should be done now, instead of earlier or later.
You can use "now is the time to ___" to warn or inspire people:
Now is the time to buy. Home prices are at the lowest they've been in over 15 years.
Now is the time to invest in solar power initiatives.
Here are several examples from a famous speech from 1963 by Martin Luther King, Jr.:
Now is the time to make real the promises of democracy. Now is the time to rise from the dark and desolate valley of segregation to the sunlit path of racial justice. Now is the time to lift our nation from the quicksands of racial injustice to the solid rock of brotherhood. Now is the time to make justice a reality for all of God's children.