Hi Tom,
Up to this point no speciffic point of assembly has been decided. However, as Jordan points out, Toronto and London are the points on the map that make most sense. somewhere close to the 401. I live about 2 minutes drive from the 401. In 2013 when we made our way down to Williamsburg we meet at my house (3 cars) then made our way to Dan's Benz Barn and crossed the border from there, then picked up more cars along the way.
So for now (it is quite early) you should plan to meet somewhere in Toronto on Thursday or make your way to London On. for an early start on Friday morning. My plan is to leave London early on Friday morning Sept. 11th 2015 (between 6 and 7 am).
If you decide to make your way to London for an early start on Friday morning then your beat way would be to make it to the Hampton Inn on the third Exit in London (Exeter Rd Exit). The parking lot there would be a good place to assemble for the trip to the border. The Hampton In Address, map locations and picture of the hotel are below. As you can see it is right on the 401 and before the 401/402 split going west.
I like to leave that early since I like to arrive in Blacklick around noon on Friday. That however, is not a must, it would be nice to be there around noon in case Joe needs a helping hand or two to get ready for the big event.
Hope this helps.