Your choice of potting medium won't work. ALL those ingredients hold in moisture. You want the moisture to be gone as quickly as possible. Find some soil especially formulated for cactus then add perlite or fish aquarium sized gravel (sand packs and becomes concrete). I would mix Cactus soil and perlite (or gravel) at least 1/2 and 1/2.
In the wild, the germination rate for Baobobs is about 30%. They live in the driest place in the world that still supports life. Water sparingly when the growing medium dries. Remember that the most water they will ever get in their whole lives is when they are waundering around inside an elephant.
Germination time is at least 3 - 4 months.