if you see them, then it is time to pot them up and put a dome on the larger pot. Remember roots stick to the plastic cup and you will break them upon the process, so soak the cup in warm water to loosen them from the cup and do little distubance as possible. (have all ready before you start) Also, since you will soak them before you transplant, you don't need to give them much more in the larger pot. Should you put a plastic dome over, just the excess water of the soaking is enough. YOu don't want over water the new transplanted plant. Puting the dome is a good transition... upon removing the dome, you start watering little at the time.
My fingers are crossed! This is my most difficult time with them. if you water them, make sure to give them warm water, not to shock them.. as their temperature is on their 60's or so. Larger pot and soil retains more water and that is cool. their roots will grow slower. Good Luck!
I thought it was JoAnn who posted a picture of upsidedown cup with large windows for leaf to stick outside, but I cannot find the picture. if you make it, please post a picture for everyone!