We often have breakfast or tour reservations early; the least stressful and most reliable timewise is definitely a cab. Although I do have a great story about that ... we were going from POP to Kona Cafe at Poly for an early breakfast ressie; had planned to take the bus to MK & then monorail; got to the bus stop very early and ended up being the only ones on the bus. The driver asked where we were going & when we explained, he said he could take us directly to the Poly! Just a little Disney magic!