When were the Elder Scrolls originally scribed and first used for divination?

Possibly Aedric in origin, but we don't know:

"In an earlier volume I discussed the vagaries and influences of the Aedric prophesies, more commonly known as the Elder Scrolls. Readers wanting to know the history behind the highly inappropriate appellation 'Aedric' can refer to chapters 23 through 27 of my previous work for a full explanation as well as the incompetencies of my good comrade Therin of Mournhold, who named them thus."
Lost Histories of Tamriel

See also http://www.imperial-library.info/obbooks/divining_elder_scrolls.shtml.