at a stroke
at one stroke
in one blow
at one blow

At the stroke of half past eight, he has to be in the living room.

But at the stroke of six he was up and ready to be off again.

At a stroke of his hand, it seemed to open by itself.

In future, come at the stroke of one, to make sure they're long gone.

"Now that information can be passed on at the stroke of a key."

And now on a Sat morning retired they were here at the stroke of 7am.

These are people who can destroy a country's economy at a single stroke?

Then, at a stroke, something happened that gave him a powerful sense of purpose.

It was this complex that I expected to leave behind at the stroke of 40.

Where he will be the following week, at the stroke of midnight, I do not know.