Buttercream and decorating

[NCforthis2019]

I have to send In come cupcakes for my child’s birthday tomorrow - we leave pretty early 730am, I’ve baked the cupcakes alsready, can I do the decorating tonight and leave them out? Will the buttercream go bad? Thanks in advance,

Too late now but for future reference no it wouldn't go bad just overnight! There's nothing fresh in butter and icing sugar to go bad quickly unless you add fresh fruit or milk etc.