"The Mysore self-practice is unique compared to other asana classes. You practice at your own pace, by and large without interruption. There could be occasional comments from Guruji, such as, “Put it your head down!” or “No, no! Grab it your foot fingers!” or more rarely “Uh... correct.” There is little noise except for deep breathing and the occasional grunt. Mysore-style practice has both an intense quality and a quality of inward looking, of meditation. You simply do your practice, receive certain adjustments and wait for the next posture. Sometimes it is a long wait.
  Some students would come to Mysore, saying they were doing Intermediate and some Advanced, only to find that with Guruji half of the Primary sequence was where they were stopped. Guruji would not allow a student to progress without being able to successfully complete every posture. Frustrating for some, educational for others. It all depended on your mind-set." (Matthew Sweeney (2002): "Astanga Yoga as It Is", p. 4, 3rd Ed., 2005)

  "After a certain time practicing the Primary sequence, and if the ability is there, a student might begin learning the Intermediate postures. One by one  these asana are added to the Primary asana, the total practice getting longer and longer. Eventually the student would practice only Intermediate. This is referred to as splitting the practice, that is, when a sequence is then practiced separately without adding those postures on to the previous sequence.
  From one day to the next a student goes from regularly practicing all of Primary and at least half of Intermediate per session (usually over two hours) to just doing Intermediate (maybe one hour). The Primary sequence is then practiced once a week. Depending on the student, this can be a relief or a shock. The same process occurs when learning Advanced asana." (Ibidem, Matthew Sweeney, p. 7)

  "It is normal to want to move ahead, particularly as far as positive motivation and liveliness is concerned. The practice should never be lifeless, something new can be experienced every day, even if it is just a changed attitude. This forward looking attitude, however, should always be tempered with present tense awareness: stay in contact with what is rather than what should be." --- "In the Primary series there are a few core postures which are common stumbling blocks. They are Marichyasana D, Kurmasana, Garbha Pindasana and Baddha Konasana. All of these postures can be quite confronting and some time and patience is usually necessary for the body to adapt. It is quite common for a student to practice (or be taught) the whole sequence prior to exploring these core asana thoroughly. The final section of Primary is often more than a little messy as a result. Generally it is better to focus on these core postures first, rather than skimming over them to get to the finish line." (Ibid., Matthew Sweeney, p. 8)

 So, traditionally it's up to the teacher — who has the experience/knowledge, and well-being of the student in mind — when to 'receive' or be 'given' a new pose. This has some obvious advantages. The somewhat too cautious/humble student may think he/she is not ready for the next pose — or the student might be too eager to move on to difficult poses which will after some time result in problems — while the teacher can be a more objective judge of how well or how fast the student is or should be moving ahead in the series; especially in estimating the quality of breath, bandha and drishti. In reality, it is a shared responsibility. The student has to be aware and attentive of what is going on, and communicate with the teacher if there are any issues of pain or other problems. And the student should of course develop a personal home practice.

 Matthew Sweeney's book is full of useful pointers and tips on how to practice Ashtanga.

"Slow progress is good, fast progress is dangerous"  Sri K. Pattabhi Jois