I first grew the seeds in a very small pot (approx. 250 ml) until the first 4 leaves were visible. The plants were then about 3cm high.
I then transplanted them into their final 10l pot and covered them with a transparent cover to keep the humidity high.
I boiled the soil for the pots beforehand with boiling water to kill eggs and larvae of pests. Then I let the soil cool down and filled the pots.
3 days after I planted the seeds, the plants are about 5cm tall.