You want to get them in asap so they will begin to get in their and check them out. I agree with the fake egg, however, it is not necessary. Mine start laying in their boxes on their own without eggs in there. If you notice that they are laying on the floor or anywhere other than the boxes than I would put the fake eggs in to help them.
It is also a good idea to put the nest box lower than the roosts so that they wont be inclined to sleeping in the nest. Check on them the first few nights and if they are sleeping in the nest, move them to the roost. Otherwise the nest will get all poopy (a highly technical term), LOL.