DD was a little over 2 and only got them at nap and bedtime. Took it away at nap for a couple weeks and she did fine. Then we talked about it and decided she was a big girl and didn't need it at night. She got a sippy with water.
For about a weeks she'd ask for a "baba" at bedtime and i would tell her she was big and didn't need it and all was well. She's 3 now and about once every 6 months she'll still ask at night then giggle and say " I just kiddin' mommy, I a big girl now", lol