I am making a very large cake (24" x 17"), and I am using buttercream to ice it. I am not using butter in the icing, it will be all Crisco based. The only dairy that will be in the icing is the milk/cream ( approx 6 Tbls)

It is too large to fit in my fridge, is it ok to ice it a few days in advance and leave it in a cool room? Or am I risking making people sick from the icing turning?

I never refrigerate my cakes and I use milk in my buttercream. I use Indydebi's recipe and btw, she never refrigerates her cakes either.

I have kept my icing at room tempature, covered, for up to two weeks with no problems.

even if you used 1/2 butter 1/2 shortening your buttercream would be good at room temperature for a week or two. The milk/cream in there won't be a problem either. I dont' have a link to the exact science of it all, but the general idea is that the sugar keeps the milk from spoiling the icing, it acts as the preservative.

Thank you so much mamawrobin & leily. I really appreciate the quick responces. That really takes a load off my mind to know that I can get this done ahead of time and not the day of the event.