Why would that be Tim? Isn't CGM an organic that releases it's nitrogen and other nutrients over time. With CGM your feeding the soil (microherd) which in turn breaks down the organics (over time) into inorganics N,P,K and micronutrients. Now, the inorganic nutrients are readily available for the grass to utulize. The breakdown of these organics is determined by other factors also, i.e. water, heat, decomposers in the soil, like worms beetles ect.. CGM isn't going to release it's nitrogen all at once right? CGM is expensive to apply on large lawns, it may also inhibit seed from germinating just like a halts or other preemergent. If your going to use CGm as a fertilizer try and go totally organic if you can. But there are many factors that go along with your question.
cgm isn't that great as a pre emerge, unless turf has very little crab or goose pressure and turf is dense!
Never used cgm, but most organic fertilizers last some where between 4 to 12 weeks when soil temp is high enough for microbes to be active, higher application rate will give a little longer release. cgm contains only nitrogen, usually 10-0-0, and applying 20 lbs = 2lbs/m of nitrogen, way too much for spring and summer feeding. Rember, in cool season turf, 2/3 of yearly nitrogen should be applied to release in fall!
to better answer your question, you would need a sythetic fert low in N, maybe a touch of p, and alot of sulfate of potash! but how much cgm are you going to apply?
CGM goes down as a dust which makes it very available to the microbes simply because of the enormous surface area of dust. Also, CGM is more than a dense source of protein, it also is a carbohydrate source. The carbs encourage the microbes to multiply which speeds up the protein digestion and ends up dosing all of the protein from the CGM nearly all at once. As a fertilzier it should be used well under 15 pounds per 1,000. I would start at 10p/m and see if you should adjust downward.