Hmm, I think last time I was reading something incorrectly. The source that I can find that _acknowledges_ that the flight to Egypt must come after the purification at the Temple and before going back to Nazareth is by John Calvin's commentary on Luke 2:39 (http://www.ccel.org/study/Luke_2:39).
Quoted:
The departure to Egypt, I readily acknowledge, came between those events; and the fact mentioned by Luke, that they dwelt in their own city Nazareth, is later, in point of time, than the flight into Egypt, which Matthew relates, (Matthew 2:14.)