Help New Grower Problems! Please!

i have three LA confidential seedlings under a fluorecent that are like a week and a half old they were started in rapid rooters and now they are n 4 inch rockwool cubes they were just put in them yesterday.they are in a humidity dome and tray. once the roots break out of the bottom of the rockwool do we transplant them to our flood and drain buckets or will they be too small still and should be let them someone start to veg in the tray?

Bro thwy dont need the dome anymore and throw them in there. Be careful notto over water or burn with nutes. Good Luck Growing