When to make your move...to a larger grow container?

I usually just let them go until I see healthy amount of roots coming out the bottom and move them into larger pots. (I always use air pots / smart pots though making it easier to judge root density) I like to go from riot plugs to 1L air pots, and then their final pot (3.6gallon air pots) adding some endomycorrhizal each transplant. endomycorrhizal seems to work really well and the plants don't seem to slow down at all with transplant. Don't see to much of a benefit to moving until roots actually need the space, plus it's easier to water smaller pots for the short time you can. Cannabis is pretty hearty plant and doesn't need much coaxing. Roots will fill every nook and cranny it can find in the pot. I wouldn't add additional nutes unless plant is showing signs that it's actually hungry. Seedlings don't need much of anything to get rocking and rolling. Good luck and happy farming! Wishing you a healthy bounty