Use a spreader for more even results. Topdress with a fine layer of redwood or fir compost or peat moss at 1 bale per 250 sq. A compost spreader is helpful. Fall is the best time to renovate cool season grasses. Early to mid spring is also good.
Spring is the best time to renovate bermudagrass lawns.
If you have had a problem with annual weeds in the past, renovating in the spring will likely cause large numbers of weed seeds to germinate. Consider applying a pre-emergent in the spring, treating for weeds through the summer as needed, and renovating in the fall.