I'd take a boat to the contemporary and then hop on the monorail.
The standard WDW line is to allow 90 min for travel to all dinner reservations. But, you're looking at waiting for the boat and the short ride over to the CR (assuming they are counterclockwise, they sometimes go clockwise to stop at the WL first, and then your ride is a little longer...); a walk through and up in the CR to get to the monorail station; and then a wait for the next monorail and a ride around. I would probably be at the boat dock an hour before our reservation.