I will be making a cake a few days before it's to be eaten (frosting it Thursday for Saturday). I will be doing fondant circles to go on the sides and top of the cake. Would it matter if I put the circles on a few days prior, or should I get someone else to put them on the day of? I'm doing a light green buttercream cake with different color (including red) fondant circles. I was unsure if the colors might run, or the circles might fall off the sides, etc.

Also if I do the circles a few days before, I'm assuming they wil harden and be flat instead of conforming to the sides of the cake...is that going to look weird?

Thanks all!!

It's not a good idea to put fondant circles on buttercream too soon, because the color could bleed (and I see you're using red!) and the buttercream might soften the fondant - but this might only be a problem in very hot, sticky climates like mine! I assume there's some reason that you can't put the circles on the cake right before you deliver it, but if someone else is going to do it, make sure you give them clear instructions. If you're worried about the fondant drying out, place your circles on the pan you made the cake in while they dry or put them in ziplocks as soon as you've made them so that they won't dry out. If you could lay them out like you want them, you could take a photo of them and give it to the person who would be putting them on the cake on the day of the party. You might also provide them with a little bag of royal icing to use as glue - just place a few dots of the RI on the back of the circles to hold them in place, because either they or the buttercream might be too dry for them to just stick by themselves. HTH!

I've put fondant decorations on buttercream many of times with out any problems. Don't store the cake in a air tight container though, that will cause your fondant to draw moisture from the buttercream and could melt. In a cardboard cake box is the best.

When you glue them to the sides, go very light on what you are using to glue it with. I like piping gel because it doesn't take a lot and seems to hold really well. But I have used gum glue or vanilla before. But again, go very light on what you use. If you saturate the whole back of it it will take longer for it to dry, which can cause it to bleed and slide on the cake.

Just my opionion but I'd not put the fondant circles on too far in advance, especially red. I'd wait until the night before to apply them. It doesn't take long to place circle cut outs.
As for the fondant circles drying too hard, I keep mine in a closed containers so they'll stay flexible for applying. And for eating for that manner!

I've never had a problem placing them on a buttercream frosted cake in advance. I just use a TINY bit of water to adhere them to the fondant (with a paintbrush). If you just use a tiny bit, they shouldn't run or bleed. The only time I've had that problem is when I've used too much water to attach them. I always adhere my decorations right after I make them when they are still soft and pliable to form to the cake and I've had cakes sit a day or two before delivering without any problems.

Good point about not using too much glue, TexasSugar and lexi55033! But is that still true when the fondant on the cake has been drying for a few days? And warchild is, of course, right about keeping the circles in something airtight - forget what I said about letting them dry on the outside of the cake pan - too big of a PITA when you can just keep them pliable with no problem.

If the buttercream has crusted over you shouldn't have a problem with it. The buttercream will just crust more, and the fondant will dry out as well.

The only two issues I have every seen is when to much glue has been used, because it leaves the areas too wet for too long or when a cake is closed up in a cake carrier and doesn't get air, then the fondant will get melty against the buttercream. But if the cake gets air to it, no problem.

If it was me, I would have no problem putting the dots on the cake days ahead of time.

Sorry (see my signature!), I forgot we were talking about buttercream. But I'm glad to hear what you say TexasSugar, because this is something that worries me, too.

If you're frosting Thursday for eating on Saturday, then I'm assuming the cake is being baked on Wednesday? Even if you're pulling the cake out of the freezer, I'd be more worried about the moistness of a 4 day old cake. I'd at least tell the customer that it should get eaten asap.