I have been using the Sam's club buttercream for some time now, just because it's easier and everyone seems to enjoy the taste. I have a last minute cake to do this weekend, I'm all out of the Sam's stuff, and it's like 45 minutes away from me. So I figured instead of trying to find the time to get out there, I will attempt my own. Indydebi's seems to be very popular, so I decided on that. I have all of the ingredients and I was planning on making a test batch today when I realized I only have 1% milk. Can I use that, or should it be whole milk?? Also, I don't plan on putting it (or the cake) in the fridge, so how early can I make the icing? Cake will be for a party on Friday.

Yes, in fact I use skim as thats what we drink and I refuse to make a special trip or purchase for more fat. You can make the icing now if you want. Someone else will probably have a better answer, but BC will keep for awhile, even without refrigeration. Granted if its out inside your house you will notice some seperation.