They did so only after the seven years war with France was underway. If the French are already evicted they do not have a base in close enough proximity to "support or promote" rebellion let alone a "fifth column" The French settlers both in Canada and Acadia are probably left to attend to their farms and small communities the same way they were after 1763 in Canada. They will simply exchange French administrators and merchants for British ones. There will be no "upheaval" in this case. Their communities will grow and spread in this region much as they did in OTL growing to number as many as 80K by mid century, limited to the lower St. Lawrence valley, the Acadia peninsula and the isthmus of Chignecto, probably to the shores of Cape Breton and Ile St. Jean along the shores of the Northumberland strait to at least the Miramichi and perhaps Chaleur bay.
British and New Englanders will settle from Portland to the St. John River. Some may settle on the Acadian peninsula, but without a French presence, there is no reason to found Halifax, since there is no Louisbourg to counter. The French may remain at Plaisance in NFLD but it depends if they have the offshore islands to maintain their presence in the Atlantic fishery.
British settlers in the colonies only number a quarter of million at the turn of the century they still haven't advanced that far inland and have plenty of way to go before even getting to the eastern continental divide. Keeping the peace with natives as these colonies eventually reach that divide will be the biggest problem for the British. There will be no British settlers in the French settled areas, because they're French and Catholic and very traditional, and as said there is still plenty of land adjacent to the colonies already established that lie only within the domain of the Natives. Any Br. settlers will remain largely military garrisons, administrators, merchants and traders, same as post 1763.