Your doing well. with 120W i think they can handle 100% at 30-40cm as soon as next week.
I grow with an HPS 250W wich is always 100% i start with the bulb 70cm from the seedlings and then let the plant grow until canopy-bulb distance is 30cm then i move the lamp upward as the plant continue to grow. Check some of my diaries first few weeks, you'll see how 100% with 250W benefit an healthy and vigorous growth on start up, then afterward.