Ken, I would keep them at the same level as they where before potting individually. You can just add a small layer of soil mix to bring it up to the bottom of the green stems.
I usually with newly seeded seedlings have them with the others, but use a 60% shade cloth over them until they have atleast 4-5 true leaves. Where you have should be fine, but move out slowly when they have grown more true leaves. You will be surprised at how they respond.
Rick
