I know the Sith Master will probably nail this one in a minute, but I have to exchanve my 8830 for a new one

the "d" key only works about half the time, so I was looking at the desktop software and saw this option. My question is though do I need both phones available to me when I do the switch? I have to take the phone up to the store and get a new one, now unless I take my laptop with me, which I can do, and do it there on the desk at Verizon (man they would love that) or can I start the back up, and then take the phone up and bring it back and finish the process.
I have not clicked on the button for fear of starting the process and not being able to stop, kinda like a nuclear launch once its started it can't be stopped LOL..
Any help would be appreciated.