it would offer a one-time ad credit of $250 to select businesses when they spend $1,000 or more on new ad campaigns over the next 30 days.

I don't think this is going to work. Maybe if it were just a $250 credit, you could get people to come back and hope they see that they got return. But if people are already spending $0 then I don't see many breaking their decision to leave just cause there is a deal