Sacrificing an animal is compulsory upon every adult and sane Muslim
who possesses minimum Zakaatable wealth (Nisaab) on the 10th of Dhul Hijjah.
It is not necessary to have the wealth for one year as in the case of
Zakaat. (Shaami vol. 6 pg. 312; HM Saeed)
From: Al Mahmood 13 Q & A from the Darul Ifta
Mufti Ebrahim Desai