If you put the excluder in between the two deeps a week before. It makes it easier to know where the queen is when your ready to split them out. You only have to find which box has eggs to find your queen. That is how we are able to split a 100+ hives in a day. It's easier that way you don't really having to see the queens this way.
We call it the speed spliting way. It beats having to look throw two or more boxes and hoping to see the queens.