Qi is the life force or "essence" of the body, it something we are born with, and live life with, but it is also something we can develop and (hopefully master) through our M.A. training.
Qi is linked to breath and blood, so as we train we raise our heart rate, while trying to remain relaxed with our breathing, thereby generating Qi in the body.
Recognising the flow of Qi energy is not the easiest of pastimes, and requires a sensitivity and understanding of your own body, I.E. recognising the difference between the muscles jumping from exhaustion, or "tingling" from the flow of Qi. (symptoms of Qi flow or Qi development often differ from individual to individual).
They can range from a sensation of heat in the extremities such as the hands and feat, to a sense of "butterflies" in the abdomen, to a feeling of the skin "crawling", as if ants are walking across the skin.
Some people experience it fairly early in training, some take longer, many factors hinder it , such as stress, illness, diet and lifestyle.
Dont interlectualise (?) what you are feeling too much, calm the mind , calm the body and relax, You will know when you find it.