Gold1answered grow question a year ago Howdy homie.
Take a good look at the PAR/PPFD chart that comes with the light. Generally, seedlings like 100-300 µMol, veg is 400-600, and flower is up to 1000 µMol.
Personally I just set the hanging height to anywhere between 30-36 inches above the seedling at 100% intensity and just let the plant stretch up into the light. If I find that I need to adjust the light after the plant has finished its flower stretch, I'll do that.