My DstepD has had showers since she was just a few weeks old (or so DF tells me). He just used to hold her and she got used to it. I've known her since she was two and I'd say she has more showers than baths, although she does love to have a splash about in the bath every now and then. She's only recently started being able to be in the shower on her own, before one of us would always be in there with her (she didn't want to be alone in there). We intend to get bubs used to the shower nice and early too.