Wait sorry, I just read your posts in a bit more detail. You're using a nano sim? Why not just stick to that. Buy an adapter. Its like $5 off Amazon or so. I use a NanoSIM now that I got with my 5s during my upgrade (sold it immediately after launch day). This allows me flexibility to use an iPhone or any nanosim phone in the case I need it. Remember you can always go larger with adapters, but going smaller is harder unless you get a new SIM or you want to risk SIM cutting on your own.
I have something like this:
http://www.amazon.com/MediaDevil-Sim...no+sim+adapter
BTW, even if you get a new SIM, you can just tell them to activate the SIM. They don't need the phone to do that. I had to get a new nano SIM for my mom switching to a Nexus 4 last week, and we did it in store. We had her old 3GS (no data plan ever), and we slipped it in using an adapter. Got home and used the nano->micro adapter and swapped it into the N4.