A lot of advise online suggests your birds should be given a bath regularly (which in alot of cases appears to relate to 3 days), but our finches seem to love bathing so much that they let you know it, and want a bath every day. Some even try to bath in the water bottles if you withhold the real bath!
For the last few days however, the adult Cherry finches have been soaking them selfs more than usual, so much so in fact that at first they can not even fly that well.
We enjoy letting our finches bath. Most days, as soon as we put the bath on, the finches will be in it splashing away within the 1st minute.