we're going to Sanaa too so I'll be interested with the parking thing at Kidani (especially blue badge parking) even though I probably wouldn't mind walking from Jambo House to Kidani
Now going out of AK can take quite some time depending on the crowd and depending on you AK day planning
Avoid getting stuck in things like the Rafiki planet watch close to "get out of the park time", as you need to take a train back and might require a lot of time.
If you manage to arrive early, chances are you're parked close to the entrance and you'll need 5 minutes to get from the entrance to the car.
If you are parked rather far inside the lot, allow enough time to either walk back to the car, or to wait for some obnoxious guest to heed the CM's messages to finally sit or clear the loading zone ...
The actual drive to AKL is around 5-10 minutes depending on traffic, but it's pretty close together.
I wouldn't feel confident leaving the park less than half an hour before my ADR (I mean actually leaving the park, like in going through the exit turnstile)
I would give it a 45 minutes minimum (knowing that if you make it by 12:45 you might get seated straight away (again, depending on how crowded it is)