I was also going to comment that you could park at the TTC then walk to Poly then monorail to Epcot, but if you're spending the rest of the day at Epcot, I'd just park at the Poly for breakfast (no issue doing that), then drive to Epcot and leave the car there the rest of the day. At the end of the day, it's MUCH easier just walking out to your car in the Epcot lot, then having to monorail back to TTC, tram to car, etc.
In any case, as you approach the Magic Kingdom toll gate, stay to the right so you can easily get to the Magic Kingdom resort road. The attendant there will probably let you through without paying for parking (I'm assuming you're staying offsite) since you're going for breakfast, but you could pay then and just show your parking card when you get to Epcot.