She's not on vacation, she temporarily moved out in an effort to save some money by living with her parents again. Louise didn't give an estimate on her return, just said that she would keep looking for a job. That conversation happend just before Lena left for her parents, before leaving for the beach house, and Louise was already at her parents house as we learned when Ian texted her. So she has been living with her parents for at leasts 2 weeks now.
For the other person that said that Cherry was visiting her family in Europe, that was also incorrect. Cherry visits her family in Ghana once a year, so that is where she is at the moment, and that was a 3 week trip. So she has one more week of in game time before she'll be back in Baluart.