All seven days and all twelve months, spoken in order. These are sequences before they are concepts — children learn to recite them long before Wednesday means anything, and that is fine. The recitation is the scaffolding the meaning is hung on later.
Most can recite them around four or five. Understanding that today is Tuesday and tomorrow will be Wednesday comes considerably later, often nearer six.
Yes. Seven items repeat weekly, so they are rehearsed far more often than twelve that repeat yearly.