How Long Until It Works?

It depends on what she's eating during the day. However, after several nights of not eating in the middle of the night, she should be making up for it with what she eats during the day. Here are some thoughts:
If you haven't been doing a bed time bottle, try adding one (just be sure you brush her teeth/gums before bed).
If she's eating solids, she should be having food/cereal and a bottle for breakfast, a mid-morning bottle, food for lunch, a mid-afternoon bottle, dinner and maybe a bed-time bottle. At lunch and dinner you could offer a bottle too (mine usually didn't finish the between-meal bottles so they'd finish those at lunch or dinner along with their meal). That should equate to eating every 3 or 4 hours (say, 6a, 9a, noon, 3p, 6p) plus the bed time bottle.
If you're still nursing, she may need to nurse more often in the evenings. My son would cluster feed all evening -- 6, 7, 8 and 9, then sleep until 6 or 7am.
If all else fails and you've been at it for 2 weeks with no change for the better, feed her at night (but just once) and try this again in a month.

My daughter did not start sleeping through the night until she was 7 months old. The way that I see it is the baby will know when she/he is ready not the doctors. I am no professional by any means, this is just my personal opinion. I thought Isabelle would never sleep through the night, she always woke up just once (thank goodness) to eat. My pedi, and my personal doctor said enough is enough and I should just stop feeding her at night, I just could not do it. Finally one night she did it all on her own. Your little bundle may be different, but it worked for me. Don't give up hope, there is light at the end of the tunnel.

Maybe if you only feed everyother wake it will help, then oce she's ok agan then begin delaying the feed to determine if it's huger or comfort that is being seeked.

I too followed healthy sleep habits healthy child and it took us about two weeks. What seemed to work for us was to feed her more during the day so that she wasn't as hungry at night. We are generous with milk and other protein/good card combos all day. We also cluster feed in the afternoon. Her approximate schedule is 4 PM snack (protein/carb), 6 PM dinner(protein, carb, veggie), 7 PM 6 ounces of milk and she goes down for the night at 7. She typically sleeps until 6:30 or 7:00.

Another thing we tried, was not to stop cold turkey. We stepped down the feedings by offering her a bit less at night until eventually we were only giving 1-2 ounces and then cut it out completely. She wasn't very happy with us when the bottle was empty so quickly, but we did it anyway. Eventually she learned not to expect a feeding at night and that combined with giving her enough to get her through worked for us.

It is such a challenge - good luck!

M.,
My children, both, still nursed in the middle of the night at 6 months. I know what the doctors say, but it is your baby and you have to do what is right for her. I know it is tiring, but she is communicating to you the only way she knows how. I am trying to work on my nine-month old to nurse only once....so, I feel your pain, but this months are so few, so do what your heart tells you.

Good luck and know you are not alone,
K.

You don't say whether you're breastfeeding or bottle feeding, but from my personal experience, it is not at all unusual for a breastfed baby to still need a feeding during the night at least for the first year or they're well established on solids. I don't think this is a habit at this age, but rather it's an actual need on the part of the baby to get some nutrition at nite. My pediatrician had also told me the same thing, but I have long since learned that there's alot that mom knows about her kids that he doesn't. I'm also a working mom and part of my theory is that your daughter may be making up for time away by having an additional need to be near you at nite. I personally felt that when my boys woke up at nite (at least during the first year) that it was important to be there for them. When my oldest was 18 mos old, I started having my husband give him water when he was awake at nite - that worked well as he learned that it wasn't worth his effort to wake up at nite for water. So, that's something you could perhaps try with your daughter if you're determined that her needing you at nite is no longer a good thing.