Both my kids wouldn't go down for the night before 10/11pm until at least 4/5mths. It got better after that, and now they both go happily (mostly!) to bed at 7pm (aged 2 and 10mths). Takes ages though doesn't it?! They usually say "the first 12 weeks" but I think the whole first 6 months are the worst for unsettledness at night, unless you are lucky.