you want small pots -- better o2 penetration to roots.. roots, roots, rooots, roots.. all you should care about is root formation, lol. Unless you take massive cuts, a tiny seedling pot is fine. Even with large cuts the only reason for a big pot is to ensure it doesn't fall over... without roots the plant can't do shit, so you don't want to promot vege growth until it has some.
Cuttings do nothing and need virtually nothing until they have roots. So you want low VPD (high humidity) to nearly stop transpiration, which limits need to take in water, and a warm substrate (75-80f) to promote root growth. They need very little light, but obviously don't put them into flower with a long dark cycle.
when you see more than a tiny amount of vege growth - leaves will slightly fatten before the roots form and you should ignore that - you can experiment with more light and hardening them off to normal RH / VPD levels for a vegetative plant. They won't all be on the same timeline. Better to err on keeping them in low vpd / low light longer than trying to force them early. If you see stem elongation and more than a tiny amount of leaf growth, chances are there are some small, delicate roots.
just as always, have an appropriate sized pot to your plant... if it takes forever for the plant to drink down from full saturation, it's too big. Stagnant water happens whether it sits in a bucket for many days or absorbed into a solid substrate all the same.
In a nursery, they will keep it cooler above ground but keep the substrate 75-80F. Supposedly this causes more resources to be distributed to the roots.. no idea if it is true. Plants are compartmentalized, so it's not a bad hypothesis, but not something to assume without proof. If there is scientific research to back it up, worthwhile to do.
