We did some one day old on HN's, but not everyone truly picked up on them until about day seven. That was nerve racking, especially with the smaller chicks that couldn't actually move the nipple and make water come out.
Now, we do several phases:
1 day - 1 week: open waterer (they just sleep anyways so who cares...lol).
1 week - 2 week: fount waterer, with nipple drinker available (for visual only).
3 week +: sink or swim with the older chicks, immediate training upon entry, but nothing afterwards. There is no other water available, just education on how to use the nipples.
We have never lost a bird to this method and it seems to work pretty well. No vertical nips, only horizontal for us!