Hello! I have a customer with a narrow driveway, not much wider than her car. The center is grass w/concrete directly in line with her tires. Wants me to remove grass and fill with concrete. No.1 Is it too early to do this, I am in zone 6. Ground is no longer frozen, just concerned about freeze thaw etc. #2 What should my base material be, what size stone 3/8 1/2 in. How many inches of concrete are necessary, how many inches for base material. Finally, space to be filled is 3'wide x 52' long. Thank you!