OK, I've spent two trips in Kruger, in the south, one later in the year, and one in autumn. Firstly, it's important to note that even Kruger's own website says that August is fantastic, as the grass is dry, and game tends to go towards the water sources, which you can drive to. It will be chilly for the early morning game drives though.
Note that the gates at your camp (I've generally stayed at Pretoriuskop) are open from 6am to 6pm, and that's a hard shut time - later and you'll be fined. So if you want to see animals before/after, you pay for morning/night drives with a ranger, or a walk. We had all three and they were amazing, we had some of our best sightings on these drives.
Big five sightings:
- African elephant - easier than some of the others, you usually can spot their footprints (big round circles) on tracks, and other drivers will tell you where they've seen them.
- Buffalo - lots of these, especially near water holes.
- Lion - for many the dream, but last time over a week we saw nearly 20. Not many compared to say impala, zebra or kudu, but we were pleased. Even saw a hunt (they failed to catch the baboons).
- Rhino (note that the Big 5 - rhino means black or white rhinos - although black is preferred. We definitely saw several white rhino, and a couple of black ones (very lucky to see those).
- Leopard. Curse the blasted leopard. We spent a couple of days specifically trying to find these. We scoured tree tops, drove to rocky outcrops, followed up sightings from others. Nothing. And then on day 6 of 7, our hopes fading, a leopard walks out immediately in front of our car! Amazing!
But don't forget, even if you don't see all of the big five - there are so many other wonderful, amazing animals. Hyenas are incredible beasts, we had a couple walking right alongside the car, giraffes are graceful and amazing to watch, and the birdlife - kingfishers, vultures, African eagles, spectacular!
Except impala. My goodness you get sick of impala. They're like the dumb sheep of the game park ;)