One Day in the week she is in the bathroom. You must talk to her then. But you must complete alle her other tasks before you are allowed to follow her into the shower. Have fun.
Sorry, I totally confused Lynn with Leni. I guess Lynn will have its shower time in the next updates. You can meet Lynn on tuesdays in the night at the bath room but she will not shower at the moment
It is a monday. Hope it is not only by random, but here is a screen shot.