are they going to be moved in there original loft?
Take the birds and release them a few times from the new loft location, before you let them out make sure they are hungry and there is nowhere for them to go in at the old address, when you let them out they will go to the old location find there is nothing there for them and retrace there flight to where they were liberated, they will recognise the loft and come back in!
Back in the early 90's i moved 5m on the saturday, let birds out on the monday and took 3rd club on the wednesday!