A theory has been proposed concerning the Oak Island mystery with a date in the early 17th century and an association with a treasure recovery conducted by Sir William Phips. Phips located the wreck of the Spanish galleon, Nuestra Senora de la pura y limpia Concepcion, which was sunk in the Caribbean during a storm.  At least one author detailing efforts of recovery of the 'Money Pit' treasure feels Sir William may have made a side trip to Oak Island to hide treasure he didn't want to reveal to the King of England.  It seems very likely that any date for the inception of the Money Pit prior to 1670 or 1700 is too early for several good reasons.
The Money Pit legend starts with the fact that Dan McGinnis found something on Oak Island in 1795.  If he did in fact find a clearing which was being reclaimed by vegetation, and an old "ship's pulley" and rope hanging on a tree branch, we need to ask ourselves;
1) How long would it normally take for plants to fill in a clearing on the island to the point where it would be relatively indistinguishable?  Given the growth rates of deciduous plants, one would expect a figure considerably less than 100 years. After that amount of time the clearing would be filled wth small to large sized trees, and any remaining open area would likely be covered by undergrowth - effectively concealing any depression that might have been present.
2) The wooden pulley and rope would not have lasted for more than 30-40 years. Natural (hemp) rope rots when exposed to weather for long periods, and any iron components on the pulley assembly would have crumbled.
3) As the authors of this idea rightly point out, the technology to provide adequate ventilation to deep shaft mines did not exist prior to about 1680. Thus, any early dates are highly suspect unless we're to believe the diggers of the Money Pit had access to some advanced engineering capabilities. It seems that a date of between 1750 and 1790 is most likely to be accurate if there is any basis in fact to support the legend of the Money Pit.