The phrase "at some unknown point" is correct and usable in written English.
You can use it to refer to a time in the past or future that is not specifically identified or defined.
Example: "The project was delayed at some unknown point during the development process."
Alternatives: "at an unspecified time" or "at an indeterminate moment".
At some unknown point, it was cut down, possibly by Rembrandt himself, to a manageable size.
It seems that at some unknown point New York lost the markers that indicated its inclusion.
Bt10 seeds were kept around for further research, Stein said, and at some unknown point they were mistaken for Bt11 seeds, inserted into five seed production lines, and sold in lots to farmers beginning in 2001.
But at some unknown point in the painting's history, an unscrupulous dealer covered Durand's signature on the lower left side of the painting with that of another American landscape painter, Alexander Wyant.
So by the second page there we have it: one important question about when Cameron knew, the promise of a proper revelation at some unknown point in the future.
The lettering for the narration, which is being said or written by a character at some unknown point in the future of the story, is hand-lettered by you, correct?
So the deal is that at some unknown, magical point of the day on Wednesday, November 18th, registration will open up for American Express card holders.
At an unknown point in his career, Giovanni was in addition introduced to Flemish painting.
Under that system, a Global Positioning System receiver is placed at an unknown point and receives a signal from G.P.S. satellites to determine the coordinates of the spot.
It is, of course, far too early to make credible predictions about who may become Tory leader at an unknown point in the future.
The data were modeled to an initial horizontal line with a curve commencing at an unknown point (Figure 3) [7].
