I refrigerated the cakes overnight, and the next morning, I cut the 9-inch cake into 12 pieces, not 16. This was MUCH, much easier to handle, and to spread the cool whip. I also did not add the marshmallows to the petals, just used cool whip. It turned out very nice, and was actually pretty easy, since I made the slices bigger, and didn't use marshmallows. I will definitely make it again - the flavor of the yellow cake mix w/pudding, the cool whip, and the coconut was delicious!!!