This question probably has a few different correct answers. But the biggest thing is just let it finish.
I usually like to feed only water for the last 10 days or so when I know a particular strains exact flower cycle. but I've recently also had decent results tapering off on the feed too and only giving straight water for the last feed. Although the jury is still out on which i prefer. And I think part of it has to do with what nutrients you are using, and how bioavailable it all is in your media, cec, and other variables.
Also, avoid overfeeding. Feed only what the plants can use. I like to keep plants just slightly hungry if anything. Fooked that one up on my last grow too lol.