This supports recommendations for a November application of N and a caution to avoid early spring fertilizing. If you didn't put fertilizer down in late fall, there are other opportunities. If you fertilize before the end of February, the nutrients will still be available to the lawn when spring growth begins. Only consider this if you did not put down fertilizer in late fall. The slow-release action in such a fertilizer will help avoid a surge of spring growth that can weaken the root system.
Spring presents questions about the use of fertilizer and crabgrass preventer.
The problem is that two available crabgrass-prevention products, Barricade and Dimension, are only available to homeowners packaged in fertilizer. Because Barricade has no effect on crabgrass, once the weed has germinated, it must be put out on time. Dimension does have some effect on crabgrass once it has germinated, so it is a more acceptable product to use with a fertilizer in spring. This times the application close to the early May recommendation. Several fertilizer manufacturers put these herbicides into their products, so shop for brands which use slow-release forms of nitrogen.