What is the Chronology of the Feast of Holy Innocents vis a vis the Visit of the Magi as per the events in the Gospels?

On 28th December the church commemorates the Sacrifice of the Holy Innocents As per Matthew 2:16 > When Herod realized that he had been outwitted by the Magi, he was > furious, and he gave orders to kill all the boys in Bethlehem and its > vicinity who were two years old and under, in accordance with the time > he had learned from the Magi. However we celebrate the Feast of the 3 Kings on January 6th - which means by the date of Dec 28th Herod would not have known the Magi were not going to return to inform him the location of the baby Jesus. 1. What is the chronology of these two events - is it a fair assumption that the Visit took place prior to the massacre ? 2. Is there an explanation as to why these events are commemorated by the Church in a different order ?