Can I put fondant decorations on a buttercream cake The night before, or should they go on at the last min. I have made fondant cakes with 50/50 gumpaste and fondant. But I have`t tried fondant on buttercream. Thank you

Its ok . The fondant piece will stick to the non crusting bc .f u use crutsing bc u can brush little water to the pieces before attaching

Thank you, wafawafa, I appreciate your reply

All my cakes are buttercream with fondant accents. I keep my cakes in the refrigerator because I like to deliver cold cakes. Don't have a problem with it either way.

I agree w/the others
I do suggest if adding larger pieces instead of brushing w/water to stick to b'cream that you pipe on open circle of icing on it. Depending on size/shape you might want to pipe several.
There will be a suction created when you press the open circle onto b'cream holding the item in place.

I may be wrong (I haven't used fondant accents on buttercream in a while) but won't the buttercream make the fondant soft?

Good point