Storing Cream Cheese Icing
It will freeze indefinitely (say a year) if you take two steps; 

1) Seal it up good, no air exposed surfaces. Ideally a freezer bag and then suck all the air out.

2) After it thaws re-whip it just before applying. If you can, thaw it by throwing into the fridge the day before so you have more control over the temperature as you approach the time when you will use it.

Also worth pointing out that the faster it goes to frozen the more stable it will be (less separation of fat/water content, crystals etc.) so put it in the coldest part of your fridge for at least a few hours, then transfer it to the coldest part of your freezer so it makes a fast transition.