Depends where you live. since your car came with a block heater/ lower grill cover I suspect it is in a cold climate. The grill cover is only used when temps are consistently below freezing. It helps protect the charge air cooler from freezing and causing damage to the turbo. If you are in a cold climate i would advise using it.
My car did not come with one, but I bought one as I read all the horror stories about turbos freezing etc. It is a tight fit, they suggest you do the initial install when it is warm out to stretch it out a bit. Of course, I waited until it was below freezing, but i got it on. Good luck