The winter comes to an end here in Johannesburg; temperatures appr 3-17/18 degrees. I dont know if it is too early to transplant.
Olive trees:

I plan to plant them in the garden to get some growth- I got the advice to plant them on a tile in the hole.
African Flat-top Acacia tree (Acacia tortilis):
Any advice here- size of the container? Should I start to wire? When do I need to transplant?

Baobab
Any advice here- size of the container? The stem has got an angle- should I try to transplant upright?

Celtis africana (White stinkwood)
Any advice here- size of the container? Any other advice?

Any advice or links to articles will be useful