Good luck to you, remember when they get their 3rd set of true leafs you can move them into vegetation stage. If you are transplanting them, don't change the light until after they are transplanted and have stabilized. It should only take about 5 day's or so. Then you can start with the Mh about 14-16" away. The most important thing to remember is to monitor the temperature at the tops of your plants under the lights. Provide plenty of airflow through the leaf structure and you should be fine.