A friend has requested a cake for her birthday that her mother used to make: angel food with strawberries and whipped cream, already assembled. My mother used to make this, and my (distant) memory of it is that she would split the cake horizontally, make a trough in the bottom layer and fill it with whipped cream and sliced fresh strawberries. The top layer would be replaced and the entire cake would be frosted with whipped cream. I need to know how far in advance I can assemble it without it getting too soggy as I won't be present at the time it's eaten. Help, anyone?