My main hesitation came from
how a similar deal worked back in 2007 with the PRS-500. For that one you specifically had to wait for the card, activate it, and register a new Sony Rewards account using the new card to do so. BUT, this current offer doesn't say anything about. In fact, when I got approved it said "Be sure to use your card today to take advantage of this offer".
So I'm not sure what I'll so. I wish they were clearer about these things.