Step one....insert seed into rockwool cube.
Step two....water
Step three....repeat step two


Failing that.....

Fold paper towel into 2 so that you have 1/4 a sheet 4 layers deep. Wet nicely. Open one time and insert seeds. Close towel. Now comes the part you have been missing. Grab a plastic baggie and put your towel in there. Check daily for moisture, but other then that don't touch it. Let the sprouts grow dude till they form leaves, not the food buds you think are leaves. A good sprout can be about 4" long before I will do anything with it, usually with tiny roots already branching out from the tap root and that's from the paper towel method. Plants need nothing but water for the first couple weeks anyway, so there is no reason to be so quick to transfer them. Make sure they are nice a juicy before you transplant.

Personally I would just stick the seed about 1/2 down into the rockwool and it will be just fine from there on out. No reason to even transplant.