The long-used route between Lake Ontario (which receives the river waters via the Falls at Niagara, a bit of an obstacle to navigation) to Georgian Bay (basically Lake Huron) involved portaging, which was a skill well known to shipbuilding cultures of Eurasia, because, y’know, they were completely afraid of getting out of sight of land (/rimshot). The Varangians went upriver from the Baltic and portaged their ships across to descend other rivers to reach the Black Sea, for example.
[snip] History
Samuel de Champlain was the first European [known] to travel the network of inland waters from Georgian Bay to the Bay of Quinte with the Hurons in 1615. It was this same route that would later be canalized and become the Trent–Severn Waterway. [/snip]
https://en.wikipedia.org/wiki/Trent%E2%80%93Severn_Waterway
And as you know, Portage was already a well used practice by the Hurons and other tribes long before they ever arrived. Who knows how long the natives had been traveling those waterways with very finely made Birch Bark Canoes light enough to portage with no problem. Because these waterways were their freeways I would suspect a very very long time. Humans tend to always find a way to take the path of least resistance. The trade routes were already there long before anyone from the new world came.