seedling xfer to Hydroton cal pebbles

i have a 7 pot bubbler setup, utilizing Hydroton Clay Pebbles.... you can see t
the nutrient solution bubbling just below the pebbles... is this the right level?
also, i started my seeds in a pie dish between moist paper towels... can i xfer the seedlings directly into the clay pebbles ? what would be the best way to xfer them into my hydro?

thanks in advance

rock wool cubes then wait till roots show out the bottem then but in clay!