Yeah, you slightly overplanted. I use the winter sowing method for flowers and some herbs and will plant them in hunks. I sow several seeds in a spot and plant all the seedlings that grow in that spot together. I don't bother thinning or separating.

http://www.wintersown.org/wseo1/Hunk-o-Seedlings.html

There's a link to how I do it, essentially.

Rodney

Some plants do OK when planted out in hunks (like linaria or lobelia). Others I sit and (with music to sing along with,) meticulously pluck out the worst seedlings and leave one perfect seedling per cell.

After you get to know the plants, you will get skilled in planting fewer seeds per cell.

In my experience, pinks need their own individual space in the garden.

Yes you over-seeded but when they get a bit bigger and have their second leaves you can transplant them into individual pots if you have the room to keep them until they can be planted out. It will set them back a week or so but you'd have better plants. If you have a soilless mix let them dry and tghe plants should come out easily without breaking too many roots. If the roots are too tangled let the roots soak in a little water until the mix is very wet and they should pull apart with little effort. Never yank at a seedling it will break off at the root and be careful that you don't break the stem.

If you don't have room then thin them out by picking out the weakest and leaving the strongest plant

I want to encourage any new seed sower not to be afraid to transplant seedlings once they have their first true leaves. Use a pointy stick or even a pencil will do, to loosen the soil gently near the plants by digging gently under them or beside them. Wiggle the stick gently and the plants will be loose enough to drag a few aside with the pencil or stick. then handle the stem of one and lift. Make a hole in the soil of the tiny pot or cell and stick the plants roots in. If their is space around the stem just gently brush some soil with the stick around the plant. And you're done with the first one. Don't let the plants get too tall before you try to separate them. It's much easier when they're short, but sturdy enough to transplant.