Most manufacturers recommend that you start your imaging at the second molar area, which is the least practical area to start with. The tongue and the lip and saliva are a quick distraction as the scanner does not know what you are trying to image. The incisal edges of lower anterior are also a tough place to start as the incisal translucency lets the light transmit through the enamel instead of reflecting to the cameras.
A good place to start is the second premolar first molar area where you can use the tip of the scanner to displace the tongue. Reducing the focal length to 12 mm’s allows the user to hide hard and soft tissue that can impede the rate of image capture. Watch the deliberate movement of the camera that helps the user manage the area to be captured with relative ease