Is it better to stop bottles gradually or cold turkey?

Over time. Some kids don't care if a cup is substituted for a bottle & if they show no preferance the change can be quick. Some develop a attachment to a bottle & for those, cold turkey may be viewed as punnishment for unknown crimes & a reason not to trust caregivers. I put water in bottles after 1yr& put the good stuff in cups. I'm ok with kids using a water bottle for years but most toss it within wks.