MIL issues

My son is two weeks old and I'm having issues with my mother in law that I just don't know how to handle. She pops into my house throughout the week without asking and at the most inconvenient times - like when it's time to breastfeed. And when she comes over its not really to help me out, but just to hold the baby, wake him up when he's sleeping, and criticize everything I'm doing as a parent. Her unsolicited advice and frequent visits when all I really want to do is just take a nap in silence are getting more than annoying. How do I go about kindly telling her to visit less often? Or to at least schedule visits so I can be prepared? I feel like an awful person.