Since there are few things that are as unattractive as shasta daisies after they have finished blooming, I cut them back down to their base as soon as the bloom cycle is over. They will typically regenerate a small amount of basal growth that remains in place over winter.

But when you do this is up to you. You can back hard after they finish blooming (as I do), wait until you do your fall, getting ready for winter clean-up or leave them until you tidy the garden for spring.

Agree with gardengal. I started cutting back after blooming, not quite as hard as she does, but take them way, way down. If you normally cut them down in the fall and you'd like to continue to do so, that will do just fine.

Don’t get hung up on what is ’correct’. They wouldn’t care if you never cut them back at all. But they would look a mess. Just do what suits you.