Does she nap much in the day? Yes you can gradually shift it or just move it back an hour (as you would for a clock change) and she'll adjust. Might be a jig grumpy at first though if you do a big shift. I'd move it by 15 mins (plus naps and feeds too) every few days.
My 19week old baby is a brilliant sleeper, we are very lucky (god, I hope I haven't mixed things now), the trouble is, she is wanting to go to bed earlier and earlier. Tonight it was 1745, she sleeps straight through till 6/630am. I go back to work soon and won't get home before 6, DH has the same issue. Can you change a sleep pattern so that she goes down later? Thanks in advance!