mine's quite bad at the moment due to outside causes, but after years of insomnia for the past year i've actually got it working well, 11pm-8am!! What helped me was a psychiatrist and sleeping pills to get the schedule roughly in place, paired with really strict sleep hygiene (no screens, etc) and trying to get enough free time in the day to have fun and exercise.
honestly more than sleep hygiene, this probably made the biggest difference for me. if i don't have fun, my brain wouldn't shut off to sleep; and if i don't exercise at all i just don't get tired. you can try all the scheduling in the world, trying to sleep when neither brain nor body wants to is just pointless.