3 weeks into cloneing and only nub roots!!! help

these clones are 3 weeks old and they have small roots the longest the roots get are about 1cm. iv heard that there roots should be much longer and comming out of the rockwool but they are not, i want to transplant them into soil today but i dont want to kill them and the bubble they are in right now isnt doing much for them its just come clones in rockwool in a bubbledome with the vents open.

and actually today the bottom leaves on one of the clones started turning yellow.....HELP please on what to do next idk?

Are you keeping your rockwool damp?

yeah iv been keeping it to damp i think so iv been letting it dry out

Are they under lights? I don't think you wanna let your roots dry out but I don't use rockwool and never have. If there is any roots then you can transplant now.