Anybody else’s in laws just invite themselves over without warning?

My in laws keep inviting themselves over. They’ll just call/text and be like “we are coming over tomorrow” not.. so what are y’all doing tomorrow? We should get together. A lot of times they tell JUST me so I feel so pressured to be the sweet daughter n law and say oh great! ... sometimes i try to be like “ oh i can’t, i have this and this going on) and they look at me with these angry eyes like I’m a totally monster.. We just had a baby 9 weeks ago so surprise visits are tough.. having to clean the house, entertain, wake up early after getting zero sleep from baby being up at night (they like coming over for breakfast.)
Truly.. they are super rude and stay forever.

How do i get them to learn boundaries, like asking us what we are doing vs first just inviting themselves over without looking like a total winch in their eyes? Should i just say that flat out? Lol