Just make sure that you have plenty of ventilation when you change the light to MH, if not you will have a lot of dead seedlings. It will look like the Marijuana holocaust...LOL... It's awesome to see someone trying to help the MMJ community, just make sure the males get pulled before transplant, if not your efforts will be futile. Who knows you may be the next Chilli Palmer of MMJ when you are done...LOL... This sorta thing takes effort and patients, especially for your first grow. Don't get down on yourself if some do not survive or if you have to start back at square one. It took me a year to get a decent first full grow, and it's worked like magic since. If you live in the bay area, check up on Oaksterdam classes if they still run them, they are cheap for weekend classes and run about $250, and will give you that extra special green thumb!
Also test the ph levels before you switch to any other light..Too much heat with too little or too much ph will cause you to have a very bad day. But that is what we are all here for in this community, for support, and not being an a$$ hole like little Johnny Drama over there.. Seriously, this is a stoners commune, not for the ones with Jack Daniels at heart. People come on here thinking that they have all the knowledge about growing and then they put down a Greenhorn for makin mistakes... This community does not support duechbags if I may say so. WALDO! so much +rep it's not even funny! GREAT JOB!