perhaps in the 1620's one of the settlers notices some gold Jewelry on one of the visiting Powhatan Indians and inquiries lead to the location of the Potomac [Great Falls] Gold Fields.
Tales of The discovery of Gold in Virginia would be exaggerated back in England, and thousands of men set out for the Colony
The Gold in the Potomac needs to be panned , and isn't all that plentiful, Most has to dug out of a Mine.
Maybe a Miner from Wales, or Serbia notices the traces, and starts digging a mine.
This give employment to some of the Rushees, But most have to find work on the Farms, & Plantations.
This alleviates the Labor Shortage for a short time and slows down the move to Africans.
Both France and Spain have Claims on Virginia [Jamestown Fort was positioned so that Spanish Ships couldn't shot at it from the River]
Whe will also have more trouble with the Indians, so more Soldiers will be sent.
Both Spain and France will start looking closer to home for their Gold Fields,
Maybe Arcadian French discover the Maine Fields, But the Georgia Fields are to far inland,
However Spain may put a fort at the Savannah & Charleston River Mouths to enforce Its claims to the Carolinas
With Virginia moving towards the Potomac area this Early, Whe will not Have Lord Calvart getting the OTL area of Maryland.
Instead after the 1630 War with Spain, Lord Calvart is given the area around Fort Savannah, newly gotten from Spain.