Cactus / repotting time

It is still in winter but I have started the repotting of asterias.
Winter in here is moderate, no snow and no ice.
Asterias seedings will grow very fast in September if I repotted them now.
The photo is A. asterias cv super kabuto sown seeds on 23/08/2013, in a 10 cm square pot.
I can see some of good ones in the pot.