Seeding fescue lawns in the fall is a must.  Seed is usually laid after the core aeration or with a power seeder, followed by applying a starter fertilizer.  The most important step after seeding is to properly water the seed.  Each lawn will differ, but the key is to keep the seed bed moist without over watering and you should see new grass in 2-3 weeks. The best time for seeding is in the fall, and may also be done in the spring.