At the first

At the first
 

p.11
-'Yes, my Lord,' whispered Bellatrix, and her eyes swam with tears of gratitude again. "At the first chance!" "You shall have it, said Voldemort.

What does AT mean?

At is a very common word in English which usually has something to do with a destination or to be on the brink of. Examples: I'm at Broadway and Third Street. He is at the point of discovery. This destination can be a physical as well as an abstract place.

Thank you; but for the original meaning of the sentence, does it mean

-I will do this thing when the chance presents itself to me?

Yes, that is what it means. When the opportunity presents itself--at that moment.

Thank you.