Hi and welcome. Its usually recommended that you bathe your baby about every two weeks. Once a week will dry their skin out, but as we all know, sometimes its necessary. Some opt for once a month, but I think that the babies get uncomfortable, and stinky if you wait that long. Our Zig is about 5 months and we go for Tearless Shampoos, the flea and tick scare me since he's so young. Oh, and don't forget to brush her as often as possible. We try to do it every couple of days, because if we did it everyday, he would riot.
Hope this helps.