Some beekeepers may be ready to add a second box to their packages.
Don't get hung up on the thought that the bees have not finished the outside frames. The bees never finish the outside frames unless you move it. Switch out the outside frame with a frame that does not have brood on it, just nectar and / or pollen.
When you add a second box, take a frame the bees are working on, that has pollen and nectar on both sides. Move that frame into the middle of the second box. This will bait the bees to move to the upper box. You will now have nine frames in the bottom box. Space the frames out evenly and run nine frames in the bottom box. If you are drawing out new foundation move the feeder pail to above the second box. If you don't have a deep box to cover the feeder pail, use two empty supers. Continue to feed until the bees have finished drawing comb.
If you look at the bees and and think to yourself, wow there is a lot of bees in here. Then add your second box.