I can help you with this one. I would do the taxi route if you don't want to be stressed.
We were there last week and had an 7:55 PS for Donald's. We were at the WL bus stop by 7:25 and caught the first Animal Kingdom bus which came around 7:30. (I had asked at the desk and was told the first bus was at 7:30. Another family with an 8:00 PS had been waiting at the stop since 7). Unfortunately, it had to go to Fort Wilderness before going to the Animal Kingdom. It easily took 25-30 minutes to get to the AK. We arrived at 8:05 and even though AK doesn't open until 9- it was a bit chaotic. They let you through the main gate but then you wait in a crowd until your name is called (make sure you check in with somebody after you get through the turnstiles) and they escort you in a crowd of 18 or so to Dinoland. I don't think we were seated until 8:25 or so. Given this was our first visit to the AK, we felt rushed since we wanted to get on an early Safari ride.
So, long story short, in the future, I would take a taxi so I would be right on time and get seated on time. If you are seated right around 8, you should have no trouble being done by 9- and still have a leisurly breakfast with good character interaction.
Even if you are late for a PS, the will still seat you- it is Disney after all.
Have fun!!