Real estate transactions did use the lot at the corner of Water and Third streets as a referent for other lots. We’ve already seen examples of John senior’s mention of “land owned by me” and the like. Later, we encounter “the homestead of my late father John Shackford” and “the old homestead of my father the late John Shackford.”
Yes, homestead.
After considering the 1806 Samuel Wheeler house at 9 Washington Street and the Federal-style 1805 Hayden (the oldest two-story dwelling in town), the circa 1807 Lewis Frederick Delesdernier on Franklin Street, the 1810 Jonathan Weston, 1820 Daniel Kilby, and 1821-1822 Stetson-Starboard houses on Boynton Street as well as an 1812 Cape on Washington Street, the 1816-1818 Dr. Micajah C. Hawkes on Shackford Street, 1819 Jonathan Venzim-E.E. Shead on Middle Street, and 1821 William Bucknam and Captain Joseph Livermore houses on Key Street, I’m confident that ours predates them and may indeed be older than 1803, as the routing of Water Street route proposed.
I’m willing to venture 1780s. Feel free to argue otherwise.
As for time? An Eastport Sentinel article on the Wheeler house, March 29, 1882, mentioned that under the ownership of Bion Bradbury, the home “was changed by the substitution of a pitch roof,” among other modernizations. I hadn’t really considered the pitch of our roof until this but now realize it is lower (or was, before our own modernizations) than many of the later structures in town. The Federal-style houses, of course, are an exception.
Jnana's Red Barn 
Love it! If I may be able to share an idea. Please, save a piece of that rafter/timber if not in use, for future generations. It would look lovely displayed in a glass or acrylic box.