OK I own a 32Gb iphone 4, chock full of goodies, and in a few minutes the courier is dropping off a brand new 64Gb 5S

ordinarily I'd just follow standard operating procedures :-) BUT my appleId is already maxed out both on devices and computers

any advice on how to proceed before I do something I might regret?

I think the 5S needs a different sim, which will have to wait until I get to a telecom shop tomorrow, but is there anything I need/ought to do before asking telecom to switch me over?

cheers