We choose our battles, sleep isn't one of them. It was years though but I'm glad I didn't push it. DD1 started sleeping through just before DD2 arrived to take over, so around 2yrs 9months but could self-settle a year or so before that. She is still fed to sleep often though.

On the plus side, she LOVES bed and often asks to go to sleep before the sun has even set. It has never been a negative for her.