Days of Qurbaani
The days of Qurbaani are the tenth, eleventh and twelfth of Zil Hijjah. The first day is better than the second, and the second better than the last.
Time for Qurbaani
In towns and cities where Jumu'ah and 'Eid are performed, Qurbaani is not permissible before the 'Eid salaat. If the Qurbaani has been offered before the 'Eid salaat, it will have to be repeated. Therefore, the time for Qurbaani commences after 'Eid salaat on 10th Zil Hijjah until before sunset of 12th Zil Hijjah.
It is permissible, but not preferable to perform Qurbaani at night.