Get System date

Is there a way I get the current date from the commputer and have somthing only render on a cerent time of the year. I am trying to make my christmas tree render and I only want them to render on the month of december. I only want people to be able to see it in december. I have the rest of my script in c# so if any one can recomend away i would love it.

System.DateTime.Now