How soon can you give a seedling open air and light?

I have 6 freebies from my last order. 2 amnesia's 1 Green crack, 1 Mozerello, 2 Jack Herrer. All popped in paper towel about 10 days ago. Had dark colored cups on top to hold moisture and darkness until they broke the soil, (3 days). Then for the last 7 days had clear cups and T5 lighting about 3' above. " Didn't want to expose them to too much light at once. I see dispenseries keep light about 3ft above at beginning. Some are starting to stretch a little too much. so this morning I pulled cups off and dropped T5 within a few inches. I have a few grows under my belt, but I would bet some of my methods have cost me time, and money.

Soil is fox farm happy frog mixed with seed starter. Shoot holes in my process and tell me better ways,,lol Keep insults to a minimum.

You don't want to cover seedlings with domes or cups. That can introduce dampening off and kill them quick. As far as the stretching is going, they reaching for the lights. Lower them to within a few inches and raise them as the plants grow.

What Blake said, and when you transplant you can bury the whole stem to shorten the height a bit.

When my seeds pop i let them get about 1/2" long while the bean is still on i plant them root in first. As a bird needs to peck its way from a shell, in my heart I believe the seed should push its way up through some dirt. In soil they are exposed to air, and pushing through the dark for some light. So to answer your question A.S.A.P.