Hiya - congrats on the new baby. I'm only 12 weeks in with my first, but over the last two weeks we've really had a breakthrough. Bea is an active baby and would just stay up for hours until I realized I HAD to put her down as she'd never fall asleep on her own. From the day we started the new routine it's been great. She gets up at around 7am, goes down again at around 8.30. She wakes up again at around 10.30, is up for no more than two hours and is back to sleep before 1pm. She takes a third shorter nap in the afternoon and then sometime around 5.30 I run her bath. I bath her, shove her in pjs and feed her - or if she's recently fed, my husband will read her a few stories (she's not a fan of stories from me as she'd rather I just fed her). When she sleeps, it's in her cot with the curtains drawn with her dummy and bear, same routine. Today she cried, maybe, 10 minutes total. I don care if I'm a bit housebound - it's totally worth it for the peace!!
Sorry for the long post, I just wanted to share with you what works for me as it's totally made a difference in my quality of life - my Bea without good sleep is HELL to be around!
The most important thing I learned is to limit her periods of wakefulness to 2 hours.
Good luck!