It happened 5000 yrs ago, when Lord Krishna sent Uddhava, who was his close associate and a very wise man with so much of wisdom of many techniques and meditation to the place of gopis and gopas, who were full of devotion, always singing and

Recited by Gopis to protect baby Krishna from all ills after Putana's (Avidya / ignorance) attempt to harm him.

Venu Geet appears in Srimad Bhagwatam's Canto 10. It is an account of the Gopis of Vrindavan's reacting to the sound of Krishna's flute as he herded cows in the surrounding jungle.