What is your soil temperature? Up here we had ryegrass germinate in the last 7 days. Soil temp yesterday was 59. Tall fescue may be a bit slower. Be sure to use plenty of seed, plenty of water, starter fert and good soil preparation. Seeding now should work fine--however--as the weather cools off and you start to get frost at night, germination and early growth will be slow. Growth of cool-season grass is very slow below 45 degrees...if day temps stay below 45...don't expect much.
Seed will not cure a shade problem.