The last date for sacrifice
What is the last date for a valid sacrifice (for ‘Eid Al-Adha)?
According to several of the Companions and Successors, the last date for sacrifice is the last day of the ‘days of tashriq’ (the last of the three days following ‘Eid i.e at sunset of the thirteenth of Dhul-Hijjah). This is the view held by Shafi‘is, an opinion of the Hanbalis, and the opinion chosen by Ibn Taymiya. Their evidence is the hadith narrated by Jubayr Ibn Mut‘am: "All of the days of Tashreeq are for slaughtering" (Ibn Habban); and ‘Ali ibn Abu Taleb narrates: "The days for slaughtering are [’Eid] al-Adha and the three following days."
With that in mind, it is preferable to hasten with slaughtering before the sunset of the second day of Tashriq (i.e the twelfth of Dhu al-Hijjah) to avoid differing with the majority of scholars.
God the Almighty knows best.