Rockwool starter cube question

[stickywicked]

Started my cubes in rockwool,soaked to 5.5ph, put in a tray under T5's. The problem is trying to figure out when to water again. The cube feels moist on the surface, so I let them go overnight and in the morning everything is laying over. Is there some technique,secret, magic word? Also when watering do I pour directly onto the rockwool cube or into the tray in which the cubes sit? If so how much? Do I leave them in the water? How long?
I thought the seedling thru veg was the easy part.