It’s getting late. We must “be off” now. Which of the following can’t replace the underlined part?

My grandma started using Weibo at the age of 70. She always says it’s never ____ old to start doing things.

I’m still working on my project.—Oh, you’ll miss the deadline.Time is ________.

There is no point advocating banning smoking in public ________ the law is introduced

Yesterday I was about to leave for the market _____ my boss called and asked me to go back to the office at once