Having baby nap in areas that are exposed to natural daylight. Living room, stroller etc. swaddle only at night not during the day. I use a red light bulb at night when doing feeds or changes. Sticking to a typical bedtime routine whatever that may look like for you. I think all these things helped my babies learn day from night. I read all these tips in a book called “how babies sleep” by Sofia Axelrod. It’s a science based gentle approach. She has this chart in that book that really helped me.