If the Corn Gluten Meal is being used as a pre emergent "weed" control why plunk more down in October when most likely no more "weeds" will be growing in your soil?
How long any "fertilzer" lasts, or is of benefit to the plants growing in that soil, depends on the soil. Plunking down any "fertilzer" on a soil lacking adequate levels of organic matter means the nutrients not utilized almost immediately will be washed out of the soil and into the ground water while a soil with adequate levels of organic matter can hold those same nutrients in place longer.
I find that feeding my turf, on my Lake Michigan beach sand soil, is only necessary once a year, in mid to late October. Even though the humus levels in the turf are only in the 2 percent range nutrient levels stay at good levels all year, at least according to the soil tests I have had done at different times of the year, in different years.