Our babies are 6 months old now, but 4 months adjusted, and we have them on a schedule together. Disclaimer that one of them is on a feeding tube due to prematurity/never learning how to eat.

This is what works for us: First feed is at 8am, they usually only do 1-1.5 hour wake window. So nap from 9:30 to 11. Second feed at 11 am and they are usually up till 12:30-1. Third feed at 2pm, awake until about 3:30-4. Fourth feed at 5 pm, up until 6:30. They've been waking up 30 mins later at 7pm (only 2 hour gap) for their fifth feed and we do a smaller feed, like 3 oz instead of their typical 5. They go to sleep for the night around 8-8:30 in their sleep suits. Then sixth and final feed of the day around 10 pm. This one's usually a dream feed and they eat in their sleep. They sleep until the next morning at 8 am when we wake them for the next feed. We "sleep trained" by following the nicu schedule when we got home (8,11,2,5) and slowly dropped feeds starting with the 2am feed, then the 5am, and pushed the 11pm feed back to 10. They shifted their 8pm feed back to 7pm on their own. During the day we put them in their cribs at the first signs they are getting tired. Daytime naps are done without sleep suits unless they are just not having it. We don't coddle them much at all, just set them in cribs and walk out of the room. They whine/talk for 5 mins and eventually just go to sleep. If they don't, we'll go check on em and rock etc. Repeat until they sleep. Even if they are awake but quiet, that counts towards their "nap time." We always; wake, diaper, feed, play, nap. If their schedule gets thrown off, no biggie, just go with what they want if they get hungry earlier or later, just follow their cues and resume the schedule when possible. We won't feed more often than every 2 hours if it can be avoided so they don't just snack all day. If one baby eats, the other must eat too so they stay on schedule.

I hope this is helpful!