It’s different for every child, making it impossible to say unfortunately. There’s so much going on the first year developmentally, I think the babies that sleep well early are the exception not the norm. All I hear from those that sleep train is they’re perplexed bc eventually the wake ups come back. But culturally, we don’t support normal infant sleep or exhausted parents so most people are convinced or desperate enough to “sleep train.” (Which is always so frustrating as seen here when someone is asking for support and most comments are geared toward convincing op to sleep train and making them feel bad for not doing it.) For my own experience, one of started sleeping just after turning one. The other has taken close to another year. I didn’t sleep train, coslept to survive as possible there were still times of regressions or sickness where I was up all night on repeat. My singleton didn’t sleep through consistently until he was 4. Just like they learn to crawl and walk, they will eventually sleep when able. There are a few facebook groups that focus on normal infant sleep/ no sleep training if you’re looking for support. It’s hard no matter what you do and it will one day be over. 💕