You don't always have the option to start a project using Model Builder. This also means you won't have a default image overlay for your project.
You can add a Database data source to your model to get the ground imagery.
From the DATA SOURCES panel:
Add database data source
Connection Type: Bing Maps [from the pull-down]
Name: imagery [rename as desired]
Tile Level: 17 [default]
WARNING: If you want to change the Tile Level higher than the default 17, I suggest incremental updates as the size [area] of your model, as well as your network environment will determine how long this update can take. I have had users complain of 20+ hours to finish a lever 19 for a very large model.
Note: You can also turn down the resolution of your model to improve performance. This is especially helpful while laying out your model, and in very large working areas. It can significantly reduce your regen times as well.
Note Note: This imagery data comes from the BING Map servers; you will only get what is currently available via BING Maps.
See it live: https://knowledge.autodesk.com/community/screencast/de0f98ab-58d0-4297-93cb-6467719dd084
Willy Campbell