.

When you see a shit load of roots

Put your hand over the cup with the stem inbetween your flip em pff finger lol and your index finger, turn the cup upside down ( this works for soil) and lift the cup off your roots.

Place in already prepared new bed

 

Might have a problem with that unless the roots come out of the drainage holes in the bottom.

When the leaves start to sag I believe its either a sign of overwatering , well, lots of things, but if you've been doing everything right so far and the plants are LARGE, and the leaves start to droop, could be a sign of too many roots.

I'm actually interested in another way of telling when its time, because seeing a shit load of roots isnt always the best

 

I've always loved peat products for this very reason.

I plant my germinated seeds into an expanding peat pellet, fully expanded of course.

Then as soon as I see a single root poking through, I plant the whole thing into a medium of choice inside a medium sized peat pot. Then when I see the first sign of roots poking through these, I transplant to the final destination.

Pictures of both products can be seen in my grow linked to below. Very cheap, effective, and practical solution to transplanting. My babies never suffer from transplant shock because they dont even know that they've been transplanted.