According to the Liddell and Scott lexicon, the word σημεῖον (the usual Greek word for *sign* and root of *semeiotic*) was also used by Aristotle for a mathematical point, or a point in time. In this sense it was synonymous with στιγμή (*stigma*).

Now upon a continuous line there are no points (where the line is continuous), there is only room for points,— possibilities of points. Yet it is through that continuum, that line of generalization of possibilities that the actual point at one extremity necessarily leads to the actual point at the other extremity. The actualization of the two extremities consists in the two facts that at the first, without any general reason the continuum there begins while at the last, equally without reason, it is brutally, i.e. irrationally but forcibly cut off.

— Peirce, “PAP” (R 293, 1906); NEM 4, 330

The same goes for time and semiosis.