Point to another server’s databse

I am movinf my server to a new server but I would like to point the current files to the new server’s databse so everybody will see the updated datase while it’s doing the DNS changes.
I edited wp-config.php with the IP:
define('DB_HOST', 'XX.XX.XXX.XX');
but it didn’t work, how can I do it?
Thanks,

Jorge