I got it partly set up yesterday. When I switched it on it gleefully found the wifi and took me through setting up a new account and downloading updates. Only after all that did I realise I had no phone signal!
So today I went online and did the SIM swap thing (SIMs are getting tinier and tinier. This phone has the nano size) and now it's fully functioning.
Of course there's still a lot of setting up to do. I have to download all my favourite apps, copy over my contacts and work out how to stop it making so much noise when it wants to notify me of something, but I'll tackle that over the weekend.