Last two paragraphs from the original post:

In time the student yogi will know if there will be a samadhi as soon as he or she sits down to meditate. Twenty gallons of gasoline will take an automobile for a certain distance only. If the motorist knows what is in the tank, he can relax. There is no need to get excited. The duration of deep meditation is already potentially there as soon as one sits to meditate after doing breath infusion.

In time one can tell by the feel of it as soon as one sits if the dhyana will be sustained and if it will be then that is samadhi and one will then be in a more relaxed state and will be able to psych out objectively what happens.

Suryananda's Leveled Practice Expansion:

At my level of practice, say beginner to lower intermediary a more targeted observation or detection regards the atmosphere within the psyche during breath infusion sessions.

Upon adequate infusion of the psyche there comes a time within the course of practice when it can be noticed that the psyche is sufficiently infused to allow for an appropriate meditation session according to inSelf Yoga, as a stable mind-field allows for retraction at the back of the head and even naad sound tuning.

When that condition is attained, for me it is also possible to already hear the transcendental sound vibration. Both the physical and subtle bodies will feel differently, from having had heavier and or negative elements expelled through the pranayama process. Then, I know that the meditation session will take place at a relatively higher zone of consciousness as well as being overall more extendable in time.

In order to develop the necessary sensitivity for the detection of the nature of the content energy of the psyche, the yogi must have advanced beyond conventional rising of the life force which is based on the linear axis from the base energy centers to the higher centers of the head. By then there is an internal understanding of different psycho-physical locks or pressure valves, of how to intuitively integrate them in the course of the session as desired or applicable, and a beginning of the evaluation of cell life force activation.