Once you’ve signed in to your Google Account, you can start transferring items that are stored on your old iPhone or Android phone (like photos, videos, contacts, text messages or iMessages*). For information on transferring other content and data that isn’t stored on your old phone, visit Google Customer Care
The transfer should take about 15-20 minutes to complete, but may take longer if you have a lot to transfer.
Tip: You can continue finishing setup and exploring your new phone’s features while everything is transferring in the background.
* iMessage texts automatically transfer to your new Pixel. For information on transferring media from iMessage and other content (such as photos on iCloud, contacts and calendars on an external account like Yahoo! or Outlook, or apps downloaded from the Google Play Store), visit Google Customer Care