It was an idea whose time had come, with or without Darwin.

这个时代到来了，不管有或没有达尔文。

youdao

But a prominent Democratic liberal said the buy-in plan was an idea whose time had come.

CNN: Clinton's Tropical Respite Gives Way To Work - 01-04-98

It argued that with ballooning health costs, national health insurance was an issue whose time had come.

NPR: Health-Care Plan: A Massachusetts Miracle?

The CIOs I was talking with apparently considered it just a good idea, and one whose time had come.

FORBES: Are CIOs Finally Embracing Social Media?