Just updating my post and all of the affirmative responses were correct. I made a $1000 payment to Oceania for a cruise I had already booked prior to the offer but not paid in full. The $200 credit was applied within 3 days. Thanks to everyone for responding.
Does anyone know if the $200 off of $1000 is for new bookings only or will the credit be given if making a payment on an existing booking that has not been paid in full?