Alright, as far as Montreal-Niagara Falls, I have no clue.....Toronto is definitely the middle city. It just has to be geographically.
To get from Toronto to NF, driving...an hour and a half if you are doing just above the speed limit (which is what i would guess they would be doing). This of course is assuming border traffic is managable. They could actually Win the game just by picking the right bridge. The Rainbow Bridge vs the Lewiston Queenston Bridge (one out of NF, NY, the other out of Lewiston NY), they are less than five minutes from one another, but sometimes the traffic difference can be hours. And you are talking on a sunday in the heat of summer. This could be huge.
I was AT joe Davis until about 1PM....they definitely had not gotten there by then. My "false" sighting at NF State Park with the decoy teams was around 3ish, I believe...which makes me think, they probably got to Joe Davis/Whirpool Jet Boat near the same area or a lttle after.
If Icould see the images closer up...and make out the buildings on the shore lines in the Jet Boat pictures, I could give you a very accurate time of day for the boat rides.
I also had an earlier question as to whether the log building challenge could be at joe davis..and I do say it IS possible...but there are not that many Evergreens at Joe Davis...its almost all maple