They germinate fine in mid to end july/august weather, just keep them covered in case of frost.
Recommended is beginning of August (depending on the chilli they take 14 to 60 days to germinate) and you want them growing nicely by summer. I have planted mid July and beginning Aug with no issues in Pretoria, Joburg is a bit colder than Pretoria so I'd say start planting beginning August if you are not using heat pads/desert dens.
An excellent resource for all things chilli is
www.chillisgalore.co.uk plenty recipes/ideas tips and tricks and they also do a pass the parcel thing all over the world (box with several types of seeds, take what you want, put some of your own in, send it on).
The mature plants stop fruiting when they hit 14'c or below. They die if they go below 4'c for several hours.
Personally love my cycads, they live forever, low maintenance and are something you can one day give your children or grandchildren.
If you want pretty just go check out your local nursery, plenty pretty things about in August/September, don't buy plants before this as they will problably not survive the winter to summer change and the change in their watering routine.