Your N recommendation would be for the entire season. For stand establishment figure .5 lb per 1000 sq ft or 22 lb per acre basis.A standard blend which you should be able to find already bagged would be 8-32-16 and apply 250 lbs per acre which would calculate to 20-80-40 NPK. Phosphorus for the most part is immobile depending on the CEC (cation exchange capacity) since you state you have clay soils it should stay put. If you can do any kind of incorporation of this fert it will have a chance to move less.The 4.7 sample may be a little low but I defer to your local experts on desired PH for your grass.Consider asking your extension about feeding one lb of N with 2-3% iron per 1000 sq ft after stand establishment 2-3 times per growing season. All N applications should be 50% slow release IMHO.You probably have a low organic matter to call for those N levels. Normally a simple formula for soil N is 10-15 lbs N available per % organic matter.(3% OM could be worth 30-45 lbsN)An agonomist would cringe at that statement as many other factors play in but still result the same approx.
