Commas are typically unnecessary when using the expressions “at some point”, “one of these days”, “sooner or later”, “one day”, or “someday” in a sentence.

Commas are typically unnecessary when using the expressions “at some point”, “one of these days”, “sooner or later”, “one day”, or “someday” in a sentence.

One of these days I will become a great engineer.

Anxious market traders will at some point start questioning the sustainability of US public finances.

There are particular sentence structures, however, where commas may be needed to add emphasis, signal a pause, add nonessential information, avoid confusion, etc.

I'll give you a pleasant surprise, one of these days, because you are the most important person in my life.

1. Commas at the Beginning of a Sentence

We do not need a comma after short introductory phrases (less than five words), such as “at some point”, “one of these days”, “sooner or later”, or “one day”.

One day I’ll be wealthy.

Sooner or later you’ll end up in prison.

Similarly, you do not have to place a comma after single-word adverbs of time, like “later” or "someday" at the start of a sentence.

Later Amy came to tell us to tell us what happened.

Someday she will come to join us.

But you can optionally include a comma to signal a pause, add emphasis, or avoid confusion.

One of these days, I’ll travel around Thailand to enjoy its pristine beaches, explore its tropical jungles, and eat delicious Thai food.

At some point, everybody worries about growing old and cognitive decline.

2. Commas in the Middle or at the End of a Sentence

In the middle or at the end of a sentence, we do not typically use commas to set off adverbial prepositional phrases of time, like “at some point”, “sooner or later”, “one of these days”, or “one day”.

Most people will at some point face difficult times.

The stock market will collapse sooner or later.

There are particular situations, however, where commas may be required in mid-sentence. For example, use commas to interrupt the sentence flow, add parenthetical expressions, clarify the meaning of complex sentences, join a series of coordinate phrases, or connect independent clauses with a coordinating conjunction.

My life turned upside down and, at some point, I decided to close my business, get divorced, and move to Europe.

The only way for humans to survive is to colonize another planet, possibly Mars, sooner or later.

When setting off parenthetical expressions in the middle of a sentence, remember to add both commas; that is, never omit one comma and leave the other.

I'll give you a pleasant surprise, one of these days, to show you how much I love you.