For early morning breakfasts in the parks you can take the resort "character buses". They begin running to MK around 6:30am (although others report 6 to 615). To Epcot, AK, and DHS, they begin to run around 7am.
We had pre rope drop ADR's for all the parks and had no problems using Disney transportation to get to them all on time (or mostly on time)
FYI - for MK, you can't get into the park before 745am. You can get there before that to get through security and get in line.
FYI (2) - If you are going to the Princess Breakfast at Epcot - be sure to give yourself a good bit of time for the walk. It's a long way back to Norway. It took us a good 10-15 minutes to walk it from the entrance (with 2 kids DD2.5 and DD6)
Hope this info helps!