Help on mother in-law!

It’s her first grand baby which I get she’s excited but... Jesus she’s driving me insane she wants everything to be her way. At 7 weeks she already brought a crap load of baby clothes and a car seat of girl stuff. She said “I have a feeling it’s a girl” and she was right but I believe it’s way too early to be giving that much stuff anyway. And my family including I had suffered miscarriages and delivering stillborns so it’s just super overwhelming with her baby craziness. She’s been pushing and pushing to do a nursery for months and I’m due in mid March I was planning on getting it somewhat prepared in January but she’s trying to come in and do it by herself today. (We both work today) She said she’s tired of waiting. How do I tell her nicely to give me space and let me do it when I think it’s right?? Oh and she’s the type that wants it done her way so I probably won’t have a say in any of it. Just like the gender reveal I didn’t want one but.