It expresses the sentiment that something should have occurred or been done earlier and is now finally happening.

अब सही समय है, बहुत देर हो चुकी है

English Usage: It is about time we addressed this issue seriously.

Hindi Usage: अब समय आ गया है कि हम इस मुद्दे को गंभीरता से लें।

A phrase used to state that something should have been done sooner or needs to be done now.

अब समय आ गया है

English Usage: It's high time we started taking care of our environment.

Hindi Usage: अब समय आ गया है कि हम अपने पर्यावरण की देखभाल शुरू करें।