Thanks everyone for advice - three points

1) - thanks to the person who pointed out that my YYZ to DTW flight is at 9:30 a.m. (lol) - that is correct, I don't know why I thought it was at 6:30 a.m. - was thinking of my recent Tokyo flight.

2) - I actually am flying to SHA - taking China Eastern (or Southern or whatever they are called) from Beijing to SHA (lol)

3) The point you've all disregarded is the Delta lady assured me by phone that they would "absolutely" take care of me if I encountered trouble with my first flight.

But it seems all but one think I should just go the night before?

Finally, does it make sense that travel agent can't add a separate LGA to YYZ on same ticket? When I went to Tokyo the guy at Amex travel was able to do it no problemo.

thanks