I've never been a big fan of sod for a small repair job. It's basically transplanting a well groomed stand of turf and putting it in a less desireable area... so your chances for failure are greater...IMO. Pick a good shade seed mix... make sure it's a good blend of 3+ types for your area, prepare the soil well and get good soil/seed contact. The proper type of seed will thrive and your customer will think you are a genious... hey 3-6 weeks isn't long to wait for the right results, is it? Hope it helps!