Hi we introduced a "dreamfeed" at about 11 weeks.
We'd tried it before then but she would either wake up or was so asleep that she wouldn't take any feed, so changed her routine slightly.
Before we would bath her at 7 then feed and straight to bed, but at 11 weeks we changed it to feed at 6pm, bath at 7pm and then playtime, where she normally falls asleep, then at 9.30pm we wake her up, change her nappy and feed her, she falls asleep again then or gets sleepy and she is then put to bed and usually sleeps for about 10 hours.
We just started doing it one day and she took to it straight away.
Hope this helps.