How often should grandparents visit baby ?

TES
Here's a good question. How often do you think is fair for grandparents to come over and visit baby. Between my mom and his mom they try to come every week. So that's two days out of seven I have to deal with people at my house. And on top of that , they come late and stay even later. I literally need to ask his mom to go home. They feel entitled because they are grandma and they want baby to know them but how often do you think is fair ? If it were up to me I would say twice a month ...