I never apply fertilizer because my yard is mainly sand and the grass grows fast enough without it.
If your yard is smaller and you don't mind mowing twice a week you could weed and feed early. Burn off any other weeds with broadleaf herbicide in May with another application in the fall.
Applying insecticide with the broadleaf helps fend off moles by keeping the grubs under control along with killing off some other annoying insects.
I would invest in a roundup sprayer as well to keep the perimeter looking nice. It also saves the time of trim mowing or running the string trimmer. Just keep up on it every few weeks, if the weeds get too tall they may need knocked down after they turn. Also worth noting that Roundup only works when the temp. is above 60º.
I use one like this -
https://www.homedepot.com/p/HDX-2-Ga...FYpIAQodJSsCFw
I have one dedicated to Roundup and one dedicated to broadleaf for spot spraying if needed between full yard applications.