Or try and put a routine in?
Dd has always slept well which is why I'm reluctant to rock the boat. She's 4.5 months old. First few nights she did 11ish-5 then we had a phase of 3.30am-10am and gradually its worked its way back to 9:30/10 - 7/8 with a feed sometimes anywhere between 4:30 and 6.
We do have a Bath/story/bed sort of routine but it doesn't make a blind bit of difference if we do it or don't, she will only nap for 30 mins or so if it's before 9.
If she's sleeping through shall I just leave well alone and hope her bedtime just gets earlier as it seems to have been doing? It's making an evening alone with Dp out a bit impossible as bedtime falls at an odd point!