You need to follow your observations and intuition.
In my experience Lithops seedlings up to 1 yo need different watering requirements from those of adult plants.
My aim in planting is to make sure my seedlings are strong enough for the summer when I cannot shield them from excessive heat, when we get a heat wave. This is why I prefer to plant in the Autumn here in Brisbane.
Maybe one solution for you is to move your seedling inside the house at night or when it's bitter cold during the day. However, they do need some breeze so you can expose them to it during the day when it is not freezing cold outside. I have lost dozens of seedlings when I followed the recommendation of reduced watering 2-3 weeks after sprouting. So I have changed my growing method to one using cotton as sprouting medium. I found it on here:https://www.youtube.com/watch?v=hnGdBFvXWYY