This usually happens pretty quickly if it was a final counter-offer. However, I have had BOA come back to me after a counter-offer and change the number to something higher. Their short sale process is incredibly bad. And lately they have been overestimating the value on properties (in my portfolio) and killing the deal for us at the last minute while concurrently pressuring the owner to do a deed in lieu.
If this was a final counter-offer then it will still have to be run by the BOA rep. and investor and you should have that done in two weeks or less.