Like wise I doubt that unit 7 will arrive in the Autumn if it doesn't arrive in summer and therefore summer 2013 is the likely arrival date. That doesn't mean that routes couldn't be started or operated from other bases.
Absolutely and W patterns, triangles and, to a lesser extent, nightstopping patterns are no stranger to the network so expect possible rejigging, adjustments and remember that GOT needs replacing unless those slots are being used for a frequency increase on other routes next Summer.