There is no set rule for when to eliminate bottles from your little one's routine. However, there are some key factors I like to think about when doing an intake with a new client. Oftentimes, ditching bottles is more than half the battle in fixing our children's sleep issues. Usually after eliminating the bottles at night, we see huge improvements and we haven't even sleep trained them, yet! Here are some rules I like to live by to guide the decision of whether or not it's time to eliminate bottles (during the day, and during the night).
Does your child have teeth? Anything on their teeth besides water in the night can cause tooth decay. It's important to only offer water after bedtime, until the morning.
Make a big deal of the teeth-brushing process and offer water after that. Repeat phrases like "we only have water in our bed/crib or else we will get boo-boos in our mouth."
I introduce weighted straw leak-free cups to my children at around 6-7 months to practice sucking water from something other than a bottle so they are more comfortable with that option in the night time, later down the line.
Prolonged use of bottles can impact oral development of the palette and jaw structure.
Is your child falling asleep while drinking milk or juice, from a bottle? Only offer it as "dessert" at bedtime, followed by brushing teeth and nothing besides water in the bedroom.
If your child is dependent on the bottle to fall asleep, they likely will want it as a comfort every time they wake up in the middle of the night. If you remove it as a sleep crutch at bedtime, they wont need it in the night every time they wake up.
Cold turkey is usually the easiest way to go (we're talking over the age of 1). It may be a hard first day or two but if you are consistent and can endure it, your child will soon forget they ever existed.
Pack up the bottles (for an older child, perhaps ages 18+ months), and explain you have to give them to a baby who needs them. Get rid of them (actually), or else you may resort to giving in and giving the bottle back to them.
If you give in and resort back to giving them a bottle in the night, they will learn that screaming and yelling for long enough resulted in winning. Be strong - you're the parent and you're in charge!