Your username change will occur when you have completed course declaration and the username task in eVision.
The username task will be generated for you in eVision when you have completed your course declaration. As part of the task you will need to supply a New Zealand mobile phone number for a temporary password to be sent to.
The first time you log in to eVision after completing the username task you will be asked to enter your temporary password. When you have logged in you will see a change password page with a box to create a permanent password.