When you have Poinsettias you should have them in pots that have drainage holes and then water the poinsettias until the soil is soaked.
Then water the Poinsettias again when the soil becomes dry.
That happens within about a week so you usually need to water your Poinsettias about once every week which is usually enough.
If your Poinsettias are in a hotter climate you may need to water them 2 to 3 times per week but in milder climates and colder weather usually once per week is enough watering.