Quite a while back
Wiki
"The earliest extant report of sunspots dates back to the Chinese Book of Changes, c. 800 BC.[7] The first clear mention of a sunspot in Western literature, around 300 BC, was by the ancient Greek scholar Theophrastus, student of Plato and Aristotle and successor to the latter.[8] The earliest surviving record of deliberate sunspot observation dates from 364 BC, based on comments by Chinese astronomer Gan De in a star catalogue.[9] By 28 BC, Chinese astronomers were regularly recording sunspot observations in official imperial records.[10] +++"
In the life of the universe, that is a nano second.
The last little ice age lasted from around 1645 to 1850. It was in effect during the winter at Valley Forge. The thames river in Britain froze solid and they had ice fairs out on the river.