Here, you can say either, "We are doing the laundry tomorrow," or "We will do the laundry tomorrow." They mean the same thing; perhaps a different connotation sometimes, but usually they are interchangeable. Can't you do this in Russian as well, for example, "Я иду вечером," it isn't present but you use the present tense anyway. Correct me if I'm wrong, but I think you can do this.