There is no "release date"This is indicated on e-Visas for India. It indicates a "expiration date"which corresponds to the date by which you must enter India to activate your e-visa.
If you have taken out a 30-day electronic visa, these 30 days start from the moment you pass through Indian immigration. A 30-day e-Visa can only be issued within the 30 days prior to arrival in India.