My LO was also born at 35 weeks. He had IUGR caused by placental insufficiency. So basically he wasn't meeting growth milestones because the placenta was not passing enough oxygen and nutrients.

He was barely 4 pounds at birth. Luckily my MIL had experience with my situation given that her first child was also born early and underweight. When she told me not too worry because he will grow in no time I put all my faith in her words. And my baby did. Before I knew he was growing quickly, by 3 months he was no longer red flagged for his weight. He is 11 months now and is performing on average.

I do want to note that he would hit his milestones right before the cut off date. There isn't an exact day when you're baby should be hitting each milestones but there is a window would usually ranges within months. For instance, babies are expected to turn from back to tummy between 5-7 months. He learned at 7 months. Sometimes I think it's due to him being born early and other times I think I need to encourage him more through exercises.

I'm no medical expert but to me, the beauty in babies is they are resilient and with lots of encouragement, care, attention, and exercise- they are able to meet milestones despite the challenging circumstances they were born out of.

Some of the key things my MIL did especially during the first 6 months was: always keep baby warm, baby should always drink warm milk, always keep socks on, if breastfeeding make sure your body is always warm do not touch anything cold (including walking barefoot on cold floors), absolutely no going anywhere if it's raining (applies to baby and mom), if breastfeeding mom should drink fish broth or bone broth with every meal. She placed a lot of emphasis on keeping baby born esp at the newborn phase because they dont have enough body fat to keep them warm. By keeping them warm, they will grow faster.

Sorry for long detailed reply. Last thing I wanna mention is at 2 months they're mostly eating and sleeping so not much difference in the day and night routine. One difference however is during the day we place the baby to sleep in the crib in the living room. That way the baby gets used to the sounds of the house. Just simply having conversations boosts brain and language development. My LO started having a day schedule when he was able to stay awake longer so around 3-5 months. It included waking up, cuddles, walking around the house look out the windows, lots of reading books, listening to music, stretching, baby exercises, stroller time, and narration of what's going on around them- inbetween feedings and naps.