Before 1604, there are no Acadians. There is no such being. By 1755, they are a people. Somewhere between 1604 and 1755, a sense of a people emerges that is different from Europe, from New France, from New England, from Micmac. Nations have flags and days the same way clothes have labels.
Labels only mean something if the clothing is distinctive.
National flags only mean something if the conduct of the nation's citizens is distinctive. The flags come after the character of the people has formed. In 1880, the Acadians chose a flag, more than a century after the deportation, almost three centuries after the first settlers arrived in Nova Scotia. It is the French tricolour with a single star in the upper left hand corner, the star of the sea. It is an eloquent statement and an elegant symbol for the Acadian people.