Your best chance to see animals from the restaurant is going to be either early lunch or one of the first dinner ADRs. Not so much due to daylight, which factors in a little later in the evening, but an early lunch or early dinner will help increase your chances of being sat at a window if you request it. When the restaurant starts to get crowded, they don't really take table requests. There are a lot more tables that aren't at the windows than tables at the windows.
With that said, not seeing the animals from the restaurant doesn't dampen the experience. The food and service are still great and there are lots of other areas around Kidani and Jambo to view the savannahs (there is an area right outside the restaurant where the fire pit is, you can wait for your table there).