There’s never a dull moment.
This is usually used as an understatement at a time of domestic crisis.

On the spur of the moment.
A spur is used to urge a horse to a faster pace or it is a geographical feature or many more meanings.  The phrase means spontaneously, without due consideration.

Western-style cowboy spurs with rowels,
chap guards and buttons for the spur straps
Photo credit Wikipedia

Up to the minute.
Modern or fashionable.

A laugh a minute…
…could be provided by entertainment or real life.

Last minute.
Only just in time.

Just now.
If now is the present, why should just now be the very recent past?

Now then.
Another puzzle.  How can you be in the present and the past simultaneously?  It’s just something people say when they are trying to get organised.

Now then now.
I knew one person who used this expression instead of “now then”.   Have you ever heard it used?

Just a minute.
A request for someone to wait a short time.  It is the title of a long-running radio game show.

Just a moment.
As before, but using a shorter time.

Before  reading the Harry Potter books, the only meaning I knew for this word was “for a moment.”
However JK Rowling’s character,  Professor McGonagall, promised, ”I’ll be with you momentarily,” meaning soon or in a moment.

I’ll be with you in a trice
or an instant.

In a tick.
This must refer to the ticking of a clock.  Most clocks tick once a second.

In two ticks…
…two seconds?

In two shakes of a lamb’s tail.
Have you ever watched a lamb sucking?  Its tail goes round very fast.

In a jiffy.
This expression has give rise to a brand name for a padded bag to send through the post.  It is quick and easy to pack a jiffy bag!

They caught the train without a minute to spare

or by the skin of their teeth. 

This is a quotation from the Book of Job Chapter 19 verse 20 (NIV) I have escaped by only the skin of my teeth.