I am making my daughters birthday cake this week and I am planning on decorating it the day before. I want to cover it in fondant. So my question is will the fondant harden at room temperture over night with buttercream underneat it? Or can I put it in the fridge over night without it hardening? I will be using MMF.Thank you.

PS First time covering a whole cake with fondant so I am new to this.

It won't harden. The buttercream underneath will keep it nice and pliable. I wouldn't put it in the fridge, personally...I'd be worried about it sweating, and it always does fine sitting out.

Just let it sit out it won't harden

Thank you so much for your replies.