If you have requested an upgrade for multiple cabins, you will be upgraded to the most premium option available. (delta.com)
You will need to request your upgrade from 3 to 21 days before your scheduled departure for international flights, and 3 to 15 days for domestic flights. (rewardexpert.com)
Within 24 hours of departure or at check - in, you can request an upgrade with miles or cash. (upgradedpoints.com)