It might help if you shared some pics.
The baby seedlings I have here at the moment... all in 4 inch pots.
Mammillaria, just barely big enough to lift the lid, pumice is screened to 1/4 inch
Typically I drop in that pumice on top of the soil when I lift the lid, one layer thick, to keep everyone standing upright and to provide a bit of a barrier to keep the top layer of soil from drying out too fast.
A second species of Mammillaria, faster and further along
And a couple of agaves that I am now watering once a week (so fully weaned from baby treatment).
