I have been trying to do the same thing but put some clones I got in without the solo cups. I checked today and most everything is filled with roots. They are in fabric pots. I have a small tent with .5 gal plastic containers which are already root bound and will have to be flowered as is as I am out room. I mix a bit of mycos in when transplanting too and they really explode. The roots are quick to take over when you let them get fully rooted in the solo cups first.In coco (pot culture),,I usaly create a big root ball in party cups first,,I let them over colonise the cups and only when it's drinking like mad and busting out of the cup do I transplant,,,After cups I do the same 4.5L pot,,,this sets the air to water ratio perfectly because the root fibers and mass stop you being able to over water ,,going into flower il transplant to bigger pots,,but at this point you can't over water or find the medium over compacted,,,once you colonise a container properly its impossible to over water,,,its important to set air to water ratios with root fibers imo