So, I did something really crazy and accepted an order for 3 cakes, two half slabs and a two tier which is due the day before I move...duh...She's already paid the deposit so I'm not going to bail last minute like this. The two half slabs are going to be done with buttercream and the two tier will be fondant. How far in advance can I do the cake and still have it fresh & decent?

THANKS

Hi jennbrownrigg - are you able to make the cake - wrap it in cling wrap a few times and then freeze it - then thaw it out the night before you wish to decorate it?
I do this with most of my cakes - even when i am not pushed for time- keeps them so moist and enables me to bake ahead of time.

What type of cake are you making to cover with Fondant - please?

Bluehue

Freezing the cakes won't be a problem. The cake that will be covered in fondant is one layer vanilla butter cake and one tier chocolate fudge. Both are good dense moist cake recipes and the fillings on both is just simple buttercream (vanilla and chocolate respectively).
How far in advance can I decorate them all?

.........How far in advance can I decorate them all?.........

I'd say you would be safe doing them on Wed or Thur for Sat delivery.
Just remember the longer you have them finished before delivery, the less time the customer has to use it up. So 3 days in your hands means only 2-3 days for them before they could run into trouble.