I would say dont transplant until they are rooting, you could be able to see when the rooting is done and you're ready to repott by looking in the little holes you punched at the bottom of the container. I waited until I could see a root in the bottom and then transplanted to a 5gal. For 10 days old I have seen some better plants but given the ammount of light you are using I can understand the slow growth lol. You're using the same fan as me, , I got like 4 though lol.