how do i stick fondant to buttercream?

i am decorating a cake tomorrow for saturday and im using fondant to decorate on buttercream..

will it be okey until saturday without anything happening to the buttercream?

i hope im making sense.. i really need HELp ASAP as my customer is picking up the cakes tomorrow night.. yayks!

TIA!

I am not sure I understand your question...
You have a buttercream frosting on the cake and you want to cover it with fondant, is this right?

Have you seen any tutorials on how to roll the fondant out? Are you using a home made fondant?

Brush a little water on the back of your fondant decos and stick them right onto the buttercream. If any of the decos are heavy, use gum glue instead of water.

The cake will be perfectly fine for Saturday. When else could you possibly decorate it???

Are you just using fondant for accent decorations? If you are, it depends if your BC crusts or not. If it is non-crusting, the fondant should just stick right on. If it crusts, you can use a little water or I like to brush a little bit of piping gel on the back of the fondant - sticks great.

my icing crusts and I always just stick em' on there...never had a problem with them not sticking or the colors bleeding or anything....I never put water on them or anything and I always put them on after the icing has crusted because I wait for it to crust in order to smooth it well.