AHow far ahead of time can I place the transfer onto a buttercream iced cake? I'm worried about the oil breaking down the sugar but I'm not really wanting to do it the morning of in case something goes wrong. Can I do place them about 24hrs before?

How about royal icing transfers onto a cornsyrup glazed sugar cookie?

Thanks!!

I have never done royal icing transfers but for buttercream transfers, I have done them up to 24 hours in advance. I always smooth them out with a hot spatula to get rid of the lines. Not saying you can't do it sooner. That is just how I do it. 

AThanks. I figure with buttercream it won't damage buttercream though. I'm concerned about the oil breaking down the transfer or causing oil spots.