Disney transportation will get you to your PS, I am absolutely certin of that (wow and you score CRT PSs, that's great!). They run special buses just so that folks can make iot to their PSs in time. OKW bus service is great, and driving to MK makes absolutely no sense at all, since you would need to park somewhere in outer space to take a tram to the TTC then monorail to the park gates; your bus on the other hand is specifically set up so that you will get tirhgt from OKW to the park gates in a very short time.
As Pete W suggests, 7:30-7:45 at your OKW bus stop should be fine. If you want to make sure, call the OKW front desk the night before and make sure that they know you're looking for the character breakfast bus the next morning.