When do you stop bathing with your kids.

So my husband and I are super clothing optional in our home and I'm on maternity leave with a nursing newborn girl so I basically never have clothes on. My 3yo girl will often invade the bathroom while we are showering or on the toilet, she will sometimes shower with us, and i take baths with both her and the baby sometimes. My husband has started to be uncomfortable with her having no boundaries and we are both unsure when to start telling her she isn't allowed to shower with dad, or needs to let him go to the bathroom alone. What are your thoughts on this. We have a very laid back household and wondering how to be comfortable and respectful of each other's boundaries and how to start teaching these things to our kids. For context my in laws are also very clothing relaxed so it's just a normal thing in our family in general.