The Quran gives no date
Harut and Marut in Babylon
Devils spread magic and blame Sulayman. In Babylon, Harut and Marut teach it only as a test, first warning: 'We are a trial, so do not disbelieve.'
…It was not Solomon who disbelieved, but the devils disbelieved, teaching people magic and that which was revealed to the two angels at Babylon, Harut and Marut. But the two angels do not teach anyone unless they say, "We are a trial, so do not disbelieve [by practicing magic]. …
Quran 2:102
Source: Quran, Ibn Kathir