There is nothing explicit in the Qur'an or hadith forbidding us from eating on Ediul al-adhha before prayer or sacrifice is done; if it had been necessary, then the Prophet (peace be upon him) would have said so, and then it would have been reported by his companions.

All that we know is that on the day of Eidul fitr, the Prophet (peace be upon him) would eat before heading to the Prayer place, while on Eidul adhha he would eat after the salah and the animal sacrificed; he would perform the sacrifice soon after the salah and then he would partake of the meat (cooked).

Based on this, scholars are of the view that it is recommended to eat before Prayer on Eidul fitr, while it is recommended on Eidul adhha to eat after the prayer and sacrifice.  

Having said this, there is no need for you to abstain from food and drinks, especially if you have delegated the sacrifice to someone else, and you are not sure when it will be performed. Sacrifice can be performed on the 10^th, 11^th, 12^th, or 13^th before sunset.