How can someone unable to see find and go through the TalkBack tutorial available on an Android device?
In theory when a blind user first starts up the phone they have the option to start talk back. When it is turned on at start up, the tutorial automatically starts.
This option is available for devices running Android 4.0 and above.
When you first turn on your Android device, you can enable TalkBack from the initial setup screen. Source
In reality sighted assistance should be considered a requirement for initial start up.
Assuming a blind user, who is key board dependent, with no previous mouse or touch screen experience. I suggest this process.
Sighted assistant completes initial set up, with feedback from blind user on desired options.
Both 'talk back' and 'explore by touch' should be activated. (sighted assistant completes tutorial)
Sighted assistant should become familiar with gestures. Combining 'talk back' and 'explore by touch' create gesture combinations that are unique and different from neither or only 'talk back' being active.
Many of the gestures on a touch screen are easily grasped by users with mouse experience. To users with primarily keyboard experience they will be unfamiliar. Before starting the tutorial, give the blind user time to practice on the home screen, and get used to it.
Once the blind user has a basic grasp of moving around on the touch screen the tutorial can be accessed in the Accessibility menu.
With some experience the blind user will be able to re-access the tutorial without assistance. I think there is a only a small window of time when a blind user can access the the tutorial without assistance and will still get value from it. For the most part consider sighted assistance for initial training a requirement.