The Transportation and Ticket Center (TTC) is near the Polynesian Resort. In fact there is a walkway from the Polynesian to the TTC. See this
map for details. You can also find it by looking north of the WDW Speedway.
The TTC is where all guests driving to the Magic Kingdom must park. From here, you will take the monorail or ferry boat over to the Magic Kingdom's entrance.
If you were to drive to the Contemporary Resort, you could easily park for your breakfast (by providing the security guard your confirmation number), however you will only be given a 3 hour permit.
You could drive to the TTC and then take the Resort Express monorail to the Contemporary but the parking lot won't open until approximately 7:30 a.m. for a 9 a.m. opening.
The first bus will come by the Caribbean Beach Resort at 7:15 a.m. You would go to the Magic Kingdom and then walk (or monorail) to the Contemporary. However, this would be cutting your reservation time very closely.
I would take a cab directly to the Contemporary Resort. To save money, you could park at the Contemporary and then transfer your vehicle over to the TTC after breakfast.