Quoting ashley + 2:" My youngest was 3ish and I don't go far, just put laundry away in the bedrooms that are next door to the bathroom. My son was probably 4."About this age. around 3 and it was only to do do quick things and she got checked on a million times. Now shes 5 and when she bathes alone I'll leave her up there and I tell her to call me when shes done but most of the time she bathes with her one year old sister so I stay in there with them.