Taking over wife's iPhone 5S importing my own contacts

Hello,

My wife has a new iPhone (7).

I've taken over her 5S, inserting my EE SIM card. The phone works fine but it is still linked to her email account and, I suppose, her Apple ID. This is even thought I have access to her Apple ID and have deleted the phone from it, using both the 5S and her linked iPad to do so. This is all with her permission!

I have an Apple ID, obviously, and would like to completely cleanse the 5S of all links to my wife's accounts and, instead, like it to mine. The first thing I would do is download my contacts from my iCloud account to the 5S

This is the first Apple device I have ever used.