Are they already in the larger RW blocks?
In my experience, the less RW in the soil the better.
Leave an inch or so of the RW exposed above the soil line- it should be able to get really dry when the soil is dry.
I have had problems with the RW being buried to deep and holdin gwater too well, causing a ring of rot around the stem, and eventual plant death. I wouldn't try to use a plant wiht its 'feet' in RW as a mother for too long just because of this, and it's one of the reasons I switched to rapidrooter plugs.
So the practice of 'elevated transplanting' applies well here.