I bathe mine every couple weeks, in the winter when it gets so dry here, it can go every 2 to three weeks. Of course there are small cleanups in between, and in the summer when someone finds something sweet and pretty to roll in, lol
there will be a bath.
One of mine is very sensitive to too much bathing and gets dry skin, one gets oily looking pretty quickly
Look for all natural shampoo/conditioners for your baby, it helps