Check out Nigel Saunders, the Bonsai Zone on YouTube - he has a few P. afra bonsai that he’s been working on for several years. Like a few people have said, the species isn’t always seen as great for bonsai, but I’ve personally seen some very impressive specimens. IMO, they do better as a larger bonsai since fine branching isn’t really something that you can get with it.
Make sure your soil is very free draining, I use a very inexpensive DIY 50/50 mix of Safe T Sorb (aka turface or fullers earth), and perlite and I’ve use it with my P. afra for years and it’s worked just fine. With this soil mix, you are unlikely to over-water (unless you don’t have drainage holes and you’re keeping it soaked) so if the leaves start to get wrinkled then you’re likely not watering it often enough. Give it plenty of sun, allow the soil to DRY in between waterings, and just let it grow and recover.
Also keep in mind that everyone has their own idea of the perfect soil mix or the perfect this or that - but ultimately whatever works for you is perfect.
GREAT START!!!