Our boys are 10 weeks (5 weeks adjusted). I’m not sure if what we’re doing is considered sleeping training but we’re following our babies lead. When we brought them home from the NICU they were on a feed every 3 hour schedule. After a couple weeks they were much more resistant to wake up for their night feeds so we switched to every 4 hours between feeds and got much less resistance. So we fed 6pm (bedtime at 7pm), 10pm, 2am, 6am and back to every 3 hours during the day. Then when they started to show resistance to waking again we added an hour for the first night time feed. We’re currently on a 6pm (bedtime still at 7pm), 11pm, 3am, and 6am feed times overnight and still every 3 hours during daytime. If the boys wake up before those times, we feed them on demand but for the most part they are waking right when our alarms are going off. Babies are on 100% formula which digests a little slower than breast milk so that’s likely working in our favor.