As Garden Knowm said a few times in this thread, Put some drain holes in the cups. Even with sparse watering the soild can remain too wet in the lower part and can lead to the plants wicking off and dieing..
It would be a shame to see such nice plants die before their time..Actually you shouldn't need to repot them for a while, I'd say wait until you have a couple of nodes before you do. It usually takes a plant that is about 8 inches tall and at 3-4 nodes before the plant will out grow solo cups.