Save your self a lot of labor and ditch the roto tiller. Get some type of sprayer, back pack or whatever and some Round Up and spray the area that you want to do. Do it right now. Then hit it with the Round Up again mid August. Now you should be ready to plant some field rye (not rye grass)or winter wheat. Try to spread the seed just before a big rain. This should give you a start for this year.