I am making a cake for a friend and am very short on time. If I finish the cake on Thursday will it still be good for Saturday? I am using boxed cake mix (only because I'm short on time) and I will be covering and filling it with ganache. Will it be okay? And am I better off leaving it at room temp or storing it in the fridge? 

Thanks!

Put it in a box in the fridge, and don't put anything stinky like fish in the fridge, and you should be fine :)