Julia - CONGRATS!!!! I know where you're at - I took the leap & purchased a sand compot! TLC??? Chuck Acker gave me a piece of advise & that's actually why I decided to take the plunge - he claims people regularly kill sands & doesn't understand it, as he has found them easy to grow. He has come to the conculsion that they are killing them with kindness, due to the price they have paid for the plant. Treat them as you would any other seedlings!
Those look nice, husky, established. The one thing that concerns me with any compot is when they're packed close together are they going to dry off fast enough after watering? will they be more susceptible to fungus problems or any other disease? Air movement is important at this satge but not to the point where it's too drying. If they were mine I would be transplanting to a bigger compot, depending on their root system maybe even individual pots.
Keep them a bit warmer than your larger plants, keep the humidity up, and make sure that they get good air movement if you do raise your humidity. Without sufficient air movement, the high humidity will cause problems... but the moisture and warm temperatures will also help them grow quickly.