Can i do this with cake...?

Yes! After baking and cooling the cake(s) for approx 15-20 minutes, just wrap the cake(s) in plastic Saran Wrap and keep in the frig until Wednesday when you are ready to frost it. Then, frost it and place it back in the frig until Thursday. It won't freeze as long as you don't put it in the freezer. Just be sure your frig temperature is set to the average temperature setting. It will be just fine. :)