For regular wintersowing in potting mix, and milk jug, I never prick them out or pot them up. If seedling are so thick as to resemble a chia pet
I usually dump the whole blob out into a flat, on it's head. Then I flip them over, cut them into hunks with a knife, (like a pan of brownies), and transplant a hunk. I've been doing this since 2006, and I assure you it works just fine. Don't sweat it.
This blob of marigolds made many pretty clumps of flowers.
Karen