When they are starting out, its very common to take 2-4 days between watering, depending on how much hydration your mixture holds. So the fact that you 'waited' 2 days for it to dry out, leads me to believe you've been over watering. Which as stated above, will cause drooping.

Roots: I wish I had my pictures of a rootbound plant. I've had quite a few that took up as much volume as the grow medium in the containers, so it would be equal parts roots and soil, basically, I would pull the plant out of the container by the stem, and the soil wouldn't move, none would fall off, and I'd have to pry the roots to get to the soil underneath The roots gathering on the bottom and then searching up or down is normal, they congregate where the moisture is, and then when they start getting dry, they go out in search of more. This is normal, and not bad.

As far as your pretty little girls go, you just switched soil, so give them a few days and let them use up the moisture you've got going now. Then maybe start them on a low dose of nitrogen, because thats all this looks like, is a touch of over watering, and a lack of nitrogen. (Btw, the over watering would be the reason you don't have enough air in your mix, but you can always stand to use more perlite)
low_rdr Reviewed by low_rdr on . Help, 3 weeks old, Stunned Growth, Drooping Leaves Hello, I'm new to indoor growing and need some advice. My 3 week old plant has stopped growing and is drooping. It hasn't shown any new growth in over a week. The PH is fine 6.5-7.0. Was using Enriched Miracle grow soil until today, i transplanted to ProMix HP. I may have over-watered but i'm not completely sure. The bottom leaves are starting to turn yellow. It's on a 18/6 hour light cycle under 400w MH. Also I had already waited 2 days for my soil to dry before i decided to transplant and i Rating: 5