Often the kittens will mimic their mother’s behaviour and start to use the litter tray to pass their waste. This is not dependent on the breeder at all and will soon be a normal activity for the kitten. There are moments where this behaviour will take time to establish and the occasional manual placement into the litter tray after feeding will aid the process.
It is worth noting that despite no direct litter training, the breeder is still responsible to provide an adequate facility for the kittens to use the litter tray. The area in which the tray resides should be kept clean and regularly cleaned. Managing the living space including the area for the litter is extremely important. Over crowding by not providing enough litter trays can also be an issue if handling many kittens and their mother. Keeping this space clean with respect to hygiene will help avoid spread of infections and diseases long term too.