What year does Sign of the Beaver take place?

The book The Sign of the Beaver takes place around 1768.  In the book the boy, Matt, states that his father and family had worked out a plan in 1768.  Matt's father had purchased some land in Maine and Matt and his father had traveled there to build a cabin and start a homestead. Once the homestead was finished, Matt's father went back to get the rest of the family leaving Matt behind to protect their new home.

The two had built a log house.  The house had temporary fixtures in the window and a clay lined fireplace.  Matt's father was supposed to be gone for six weeks.