It's true that The Victoria Secret show airs December 8th, but it's also true that it's going to be shot on November 10th, so by then there is going to be at least a single...I don't wanna think she's going to sing BBHMM, so...
They did this with Beyonce (self-titled) and Mariah's Elusive Chanteuse. There was knowledge that these albums were dropping but no one had a concrete release date. So stores will guesstimate and collect pre-sales for it to "lock in" the sale. If it turns out their guess was wrong, they issue refunds.