A. arabicum seedlings coming up

Now that I've planted the replacement set of seeds of A. arabicum, I see the big difference. These are sprouting up fast and furious. probably won't have 100% germination (seller estimates 80% germination) but I do have big fat seedlings.
Question - how big should they be before I transplant them? Now they're in little germination cups in a set-up from seedman.com, each cup is about 1 1/2" all around. Thanks.

Quick, simple question that I couldn't find anyone to answer...how do you plant the seeds? As in, do they lie horizontally beneath the soil, or vertically?

I tried to plant them horizontally, but the germination mix was kind of fluffy, so the seeds went in any which way. Not sure if it affected germination.

I always plant mine horizontally covered with about 1/4- 1/2 inch of soil and they come up pretty and straight. Be sure you keep them really warm at all times or they will rot.

Just my opinion, I would transplant them into something a little large after they get their 3rd or 4th set of real leaves. My arabicums grew so fast, I was repotting often.

They are on a heat mat to keep them warm. No leaves yet, thanks for the tip. Should I keep misting them now that they are up? The little bit of peat mix seems to dry out fast, although the plastic cover for the mini-greenhouse keeps some moisture in the air.

This is just my experience. Keep in mind I'm no expert. If it were mine, after they've all sprouted, I would take the top off so they can get fresh air. I wouldn't worry about misting them. Just make sure the medium they are in never dries out and they should grow good. Sometimes with mine if I kept a top over them to long the soil would try to get a fungus and the fresh air seems to keep that away. When they get a little bigger I'd love to see some pictures.

Because we still have heat coming on and the air is so dry, I think I'll keep the lid on a bit longer, give them a chance to get come leaves. I'll keep an eye out, I can water with a bit of peroxide to keep fungus off too. I'll take some photos when they look like plants, not just short green sticks.