You could establish a schedule to water your jade plant if it is indoors all the time, with relatively constant temperatures, low humidity and light only varying a little from season to season. It is always best to water thoroughly, then let the plant dry out rather than watering just a little bit, more often. I used to put mine in the kitchen sink and run room temperature water through it and over the leaves (use the sprayer) until it was thoroughly soaked. This is an alternative to Ken's submerging technique. Bigger plants can go in the shower.
If it is outdoors, you must watch the plant and water when you begin to see some shriveling of leaves. As seasonal conditions - temperature and humidity - change you would need to water more or less often. Also watch that it doesn't get too much if you have a rainy spell of weather. (move it under an overhang or into a covered area).
