The problem with addressing watering issues is compunded immensely by the type of soil each of us is using, also other factors such as the temps in your house, humidity, air circulation window or light stand etc. As some have mentioned, you are looking for moist but not soaking wet. Soil mixes with lots of perlite or other chunky porous material such as turface, diatomite or pumice are best as they hold moisture and allow air in the mix which is critical to minimize rot. The best way to know how much and when to water is through experience and consistency. If you are mixing your own soil, you want a mix which is at least 50% porous chunky stuff, the rest a good commercial soil. As I have stated on several threads I find that Pro Mix HP (High Pourosity) can be used straight from the bag. I have not closely analyzed the contents of this soil, but it seems much lighter than I would expect. With this mix I can put the rooted cutting in it's cup or small pot and water thoroughly, then not for a couple weeks or so. Someone also mentioned feeling the weight of the pot which is another way to know if the soil is moist or dry. Key though is to find a mix you are happy with, use it exclusively and then learn through experience how often and how much to water with that mix and with your particular environment in your home.