I think I'm going to get into an argument about my mother-in-law visiting unannounced.
What are the issues surrounding visits from your mother-in-law?
I think the mother in law is totally abrasive and rude. She can never find a right time to show herself.
It's fine to have preferences about when someone should visit your home. Visiting someone unannounced could be considered rude to a lot of people, depending on your cultural background. You should talk to your mother-in-law respectfully about how her visits create a problem for you.
Why do I need to state my preferences? I'm sure she's sensitive and I can tell her how I feel.
If you state your preferences to your mother-in-law clearly, then she'll understand what you want. You shouldn't just assume that she'll understand what you want, as that may lead to more confusion and both of you being upset in the future.