i would say the light is way to far away (you want the light as close to the plant as possible with out burning it), the fans are to little (one fan should be on the top to take out the hot air and another on the bottom to bring in cool air).
my guess is your plant is a week 1/2 or 2 weeks old, i would not use any nutes yet, thats why i would change the soil.
MG is not the best soil to use try to find some thing with out time release nutes in it.
the leaves on the bottom are going to trun and fall of its okay.
what kind of light are you running?
Get a small fan to blow directly on the plant to make the stock stronger to help support its-self durring flowering.