Pre-growth of seeds works different then with cuttings. Cuttings you grow till there is a little plant with a bit of body before putting them on 12 hours inside. If you would to this with seedings you would get enormous trees and will garanteed have height shortage. With some strains with a little more sativa it is advised to go on 12 hours right after gemination. Off course do climate and watering have influence on the height of your plant but with normale circumstances your plant will be about 120cm. The bit shorter indica strains will do with one week off 18 hours after germination to have a nice plant with body and side branches. It would be nice to have a little pre-growth then your roots will have a change to create a beautiful network.