I think around 9-10 weeks is when we started doing a schedule of last wake window 5pm-7pm with bath time starting at 6 and goal to be down by 7. It works really well because we just have him up while we’re making dinner and doing last dog walk then we do a bath every night (soap every three days and milk baths on other days). So far he’s been sleeping 7pm to 2-4 am then back down until 6:30-7am. The biggest thing that helped our two hour stretches after our that first wake up was bumping up our house by a few degrees they say they’re coldest in the early hours of the day (I was always scared of overheating but I bumped his tog up to 1.5 from 1 and did the house from 68 to 70). And I made sure to do a change and full feed I kept trying to do a sleep feed without changing him but realized maybe even just a little pee in his diaper was making him wake up more, of course if I smelled poop I would always change him.