After about a week you can test to see if your plants have started to root. Remove the humidity dome and leave it off for between twenty minutes and two hours. Watch the clones for any signs of wilting while the dome is removed. If the plants have not wilted at all then they probably have enough root development to support themselves. If no wilt is noticed leave the dome off, if they are wilted, spray the cuttings and dome and replace the dome on the tray.
Once you have determined that the plants can support themselves, stop misting the cuttings and leave the humidity dome off. (NOTE: Once the plants have roots, constant misting can actually be harmful to the plants).
If the lower leaves start to turn yellow and die, don't worry, it is perfectly normal. It is the plant feeding off of itself to sustain life, moving valuable nutrient and water from the older growth. Do not remove any dead growth until the plant is well rooted. If you remove the dying growth the plant can starve and die completely.