welcome to rollitup
what i do to figure out the right distance in EVERY stage of growth is this:
-start your lights and let them on for couple of hours
-hang a temp meter,right on top of your seedlings (or next to them of you use a closed propagation box) and let it stand there for another couple hours.
-then check the maximum temperature
Now, adjust your lamps on a height above the plants where temperature (next to the higher tops of the plant) is lower than 25-26 Celcius
->For seedlings i would suggest to put the lamp even higher (to achieve a temp of 22-23).
->after 3rd-4th week you can go as close as you want, as soon as you maintain a temperature of 25 C on the tops of the plant (otherwise they start burning on top)
Many people use a 'cool tube', which helps into ventilating the heat around the lamp and by that way, let you adjust your lamp even 5cm next to the plants without burning them!
TO avoid overfeeding this wonderful forum with the same repeated information (like those i just gave you), next time,
BEFORE YOU START A NEW THREAD, YOU SHOULD SPEND AT LEAST HALF AN HOUR SEARCHING INTO THE FORUM, because 99% OF THE STUFF PEOPLE ASK, HAVE ALREADY BEEN ADDRESSED BEFORE BY HUNDREDS OF OTHER GROWERS IN OLD THREADS.
examples
https://www.rollitup.org/newbie-central/608597-seedling-just-came-up-how.html
https://www.rollitup.org/auto-flowering-strains/611807-best-light-distance-plant.html
search for the words seedlings, lights, height
goodnight (,