T only handles SN Africa departures. You will arrive at B.
If you have your boarding pass AND no checked luggage, you follow "connections A". This is recommended, and should work 99% of the time: the IB plane will has a night stop at BRU, so that flight is rarely late.

Otherwise you 'll have to go to claim your bags, go one level up to the departures hall for check in. This would be a very tight connection. It is quite common to have long queues at border control in the early morning.

I would not advice to do seperate tickets WITH luggage on this itinerary.