Johannes Kepler in 1605 may have been the first person to know that Earth is closest to the Sun in January, and the very last slight lingering doubts about that (and many much more important facts) should have been ended by the discovery of stellar parallax by 1840.
Early astronomers naturally assumed that the planets in the solar system, (including the Sun and the Moon) orbited around the Earth. And they were one seventh or 14.28 percent correct, since the Moon does orbit the Earth.
Early astronomers believed that outer space or the heavens was heavenly perfect and unearthly and therefore everything traveled in orbits that were perfect circles, which are perfect shapes.
But that is not actually the case, and so complications in the apparent motions of the planets kept being discovered.
So early astronomers had to modify the idea of having planets travel in perfect circular orbits by having the planets travel in smaller perfect circles around points in space which traveled in larger perfect circles. And they made the planets orbit in perfect circles which were not centered on the object they orbited around - the object that they orbited around was not at the center of those perfect circular orbits but offset.
In the 2nd century AD, the geocentric (Earth as the center of the universe) model was more or less perfected by Claudius Ptoleomaeus in Roman Egypt, which was the standard concept of the universe for over a thousand years. Ptolemy had to use an elaborate system with many epicycles, eccentric deferents, and equants to explain how the planets appeared to move as seen from Earth.
And I suppose that for over a millennium astronomers could have used the Ptolemaic system to calculate when a particular planet would be closer or farther from Earth, or from another "planet" such as the Sun, though since the geocentric model of the universe was inaccurate such calculations would be inaccurate.
And the heliocentric theory of Copernicus simplified the problem a bit but the planetary orbits were still complicated.
And of course, if a planet orbits in a small circle around a point that orbits in a much larger circle, that planet will sometimes be closer to it's primary, whether that primary is the Sun or the Earth, at some times than it is at other times. So it is possible that some followers of Copernicus did discover that Earth was closest to the Sun in January before Kepler.
Johannes Kepler worked on the problem of the planetary orbits using the data of Tycho Brahe who measured the directions to planets at specific times with a greater accuracy than anyone before. And Kepler tried every way he could to make perfect circular orbits fit with the date.
And eventually Kepler gave up and tried using elliptical orbits, and found that he could make planetary motions fit the the available data. And Kepler came up with his three laws of planetary motion.
So Kepler found that elliptical orbits for Earth and Mars around the Sun enabled him to make the planetary motions fit the observation data. In 1605, 415 years ago.
The perihelion of a planet is when it is closest to the Sun,and the aphelion of a planet was when it was farthest from the Sun. And Kepler had to know when Earth and Mars were at their perihelions and aphelions to make his calculations work.
So I would say that be the end of 1605, when Kepler had completed his work on the Astronomia Nova he knew how the distance between Earth and the varied at different dates, and thus when the perihelion of Earth occured.
Of course, the sizes of the Earth and the Moon, and distance between the Earth and the Moon, had been measured with fair accuracy in ancient times, but distances beyond the orbit of the moon were still a mystery. Copernicus had worked out the relative distances between various planets and the Sun according to the Copernican system, but nobody knew the absolute distances, but nobody knew how many millions, or billions, or trillions of miles those relative distances equaled.
The first close to accurate measurement of an interplanetary distance, and thus of the scale of the solar system, was in 1672.
So as astronomers accepted the heliocentric model of the solar system, and Kepler's laws of planetary motion, they came to accept that the Earth is closest to the Sun in January. When Newton's Principia Mathematica was published in 1687, scientists who accepted Newton's laws of physics now had a theoretical explanation for why planets would orbit the Sun, and for why they would have elliptical orbits.
So as Newtonian physics became accepted, scientists became more and more certain that the Earth is closest to the Sun in January.
However, if the Earth orbits the Sun, when a star was viewed at different times of the year it would be from different points on the earth's orbit, and thus the direction to the star would vary slightly. The star would show a parallax. Since astronomers could not measure any stellar parallaxes, it was argued that the Earth could not orbit the Sun.
So astronomers who supported the heliocentric theory often attempted to measure the parallaxes of stars. And finally, in the late 1830s, Friedrich Wilhelm Bessel measured the parallax, and thus distance of 61 Cygni, Thomas Henderson measured that of Alpha Centauri, and Struve measured that of Vega.
Therefore, Kepler in 1605 may have been the first person who could demonstrate, among other things, that earth is closest to the Sun in January, and the last lingering doubts about the heliocentric theory, Kepler's Laws, Newton's Laws, and the fact that the Earth is closest to the Sun in January, should have be closed no later than by the time of the discovery of stellar parallax by 1840.