That's a complicated question to answer.
When you get to the park, check out the back of the map for the Meet the Keeper times - for the Cheetahs, Chimps, Gorillas, Elephants, Lions, Hippos, Orangutans, Tigers, and various Animal Ambassadors at Jambo Junction, the Meet the Keeper often has some interaction between the staff and animals. It might be a feeding or other stimulation, but either way, the animals tend to be more active for those couple of minutes.
Otherwise, the animals tend to be a bit more active first thing in the morning, or during a light rain.
The chances of seeing every animal - at all, let alone up and active - in one visit is very small. Take a few moments when you get to each habitat, as you might have to look for signs of movement.