DD is 16 weeks now & she's been consistently sleeping through from a few weeks old (from 10- 5 ish), she is formula fed so that makes a difference. At 12 weeks we moved her into her own room and own bed, she was waking herself up stretching out in her Moses basket and there is not enough room in our bedroom for a cot, it made a big difference. She gets much better quality of sleep & now goes from 6/6.30, dream feed at 10 until 7am.
Before she was in her own bed/room we used to keep her with us downstairs mainly because we have cats and our bedroom does not shut so we couldn't leave her there alone for fear of our cats snuggling up with her! Also, SIDs is a consideration.
We moved her into her own room & implemented the bedtime routine all at the same time, bedtime came about because I noticed that was the time she started to get tetchy, bathing her gave me something to do with her, a reprieve & bought me some time until 6, as soon as the lights went low she got super chilled & wanted to sleep.
I have to be honest I miss my baby cuddles in the evenings but she wakes up refreshed & happy & smiley every morning now so I know it's making a big difference to her.
It did take some perseverance for the first few days, sticking to the routine and putting the time into soothing her without trying to pick her up but she is a much much happier baby now she sleeps more. I would put her in bed awake, and rest my hands on hers or her chest & after some serious maggie simpson sucking on the dummy she would accept it wasn't so bad and see that I was still with her, gradually I spent less time waiting with her and now I can pop her in and leave her to it.
If she does cry/lose her dummy I make sure I am by her side as quick as I can get there as it seems to giver her confidence. I find that when she falls asleep on the bottle and I put her in her bed this is when she wakes and cries, maybe out of confusion?