In Unity, init poses are created and set by using the VLInitCamera prefab. Drag&Drop this prefab into your hierarchy.
During development, you can control the init pose by pointing the VLInitCamera towards the 3D model and by moving and placing it accordingly. Choose a placement, that gives you a nice and reasonable spot on your desired tracking target, that defines, from which point you want to it to be found initially.
More information can be found in this article on working with init poses in the documentation.
You can also set an init pose in the .vl config file directly. An example can be found in the Configuration File Reference.