Alright a last minute order for 2 cakes came in which would be picked up Jan 1 around 3pm.  Problem is I'm away from Dec 30 3pm, till Jan 1st 11am. If I bake the cakes today and have it frosted ready for fondant tom morning and have the finishing touches done by tom (Dec 30) can I simply box it and leave it in the fridge?  The frosting is swiss meringue buttercream which has egg whites so needs to be refrigerated. I always finish my cake the night before anyways and next day pick (approx 12 hours) and always leave the cake in the fridge.  Had no problem with fondant tearing etc but have never left it in for almost 30 hours. 

AThe cakes will be just fine in the fridge until Jan. 1.

Thanks just one more question...I usually leave the fridge at 38..is it better to keep the fridge really cold or slightly warmer is better? I also have the exact time (55 hours) it'll be in the fridge before being served. Im so nervous. :S

Hundreds of us have done similar to what you will do on this order.  Don't worry, everything should be just fine.

Leave the frig as is.....the more you have in it the more it needs that extra chill.  If it is more on the empty side, then warm it up a few degrees (42 is the recommended temp for every day use).