Hi Linda!
Thanks for your question. I know these last days leading up to your 1st Disney trip can feel agonizingly long :-) Just hang tight, as the song goes in Princess and the Frog, you're "Almost There!"
You should be fine just taking Disney's bus transportation. Buses begin as early as 1 hour before the park opens. I would be at the bus pickup area as early as 8am. I've never stayed at Port Orleans Riverside, but the general travel time from Downtown Disney area (where POR is) to Animal Kingdom at that time is probably 30 minutes.
Dining facilities normally hold reservations 15-20 minutes after your scheduled time, if in the event the bus is running a little late, so you do have a little wiggle room.
I would try the bus over driving, and since it's not too early before the buses run, you can save money having to pay for a taxi.
Good luck! Have a terrific time on your trip!