When do I pot it?

First time I grow corms.
They're corms from my alocasia Amazonica Polly.

The mother is poted in a mix of soil, perlite and orchid bark, but I wanna try growing at least one of the corms in pumice (semi-hydro?) to see if I prefer it or not.

But Idk when it's gonna be ready to be poted or what I need to do to help transition it?

Any tips?