i usually wait untill a bunch of roots are poking through my rapid rooter plug before i pput in soil. But as long as you have roots it should be good. Sometimes clones dont take to transplanting well and will die afterwards, this is why they say to wait for a nice root system
View attachment 2629180
this is about bare min on roots, dosent hurt to let the system develop more.
i wouldn't even bother with nutes, especially if they are going into fresh soil......the soil will have all they need to get going.