The selection would be 3 consecutive days halfway through January - Nobody has been invited yet.
It has been years since they opened up for ab initio hiring, and they've changed a lot since then. Nobody knows how they'll do their selection nowadays.
It's Belgium, so expect some bull**** ATPL theory test. They'll make up their own questions, and will ask you stuff and to draw graphs you wouldn't have had to know for the ATPLs.
Good luck if you get invited!