DD2 goes for a bath at 8pm and goes to bed about 8.30pm. She's usually asleep by 9pm (has a dummy and tends to spit it out once or twice).
We've cracked the routine but we need to bring the time down because we can't get babysitters to settle the baby, which means we effectively cannot have an evening out. After months of pregnancy and a new baby I'd really like to go out sometime!
I ought to add that she has two evening bottles (number 2 milk, 7oz each time) and sleeps through until about 6am. We have tried putting her down after the first evening bottle (ie about 7pm) but she catnaps and wakes up, presumably wanting the secnd bottle.
I have to say I think this is a little bit ambitious for 12 weeks. At this stage I would have given a lot to have the sort of routine that you do with the LO sleeping through from 9pm to 6am . My DD is now almost 6 months and we are at a stage where she usually sleeps from 7/7.30pm ish to about 6/6.30am ish. But this is a fairly recent thing - we got there, I think, by really upping the milk supply during the day (long bf at about 5pm and 7pm) and eventually she stopped waking at 9/10pm. So sorry - I'm not much help, except in the sense that we did get there a bit further down the line, so you maybe don't have too much longer to wait for that night out.
I'm wondering if you are expecting your dd2 to fit into the schedule that your dd1 did? I only say this because our dd1 was a very "easy" baby - slept for hours and hours at night and napped well in the day.
Dd2 was entirely more active. I was keen for an earlier bedtime, but she loved being up and about in the evening. It frustrated me at the time, no end. Even now she needs far less sleep than her sister.