12 month rolling with future cells already in place

Trying to set up a 12 month rolling sum. However, the only issue with it is that there a re future date cells already in place (august through December of this year). Is there a way to have a formula automatically ignore these by using todays date or something? That was the person using the workbook doesn't have to delete these columns and re-add in the future? Hopefully I was clear enough. Can provide more details if need be!

Thanks.