Bottle in American Sign Language looks like you are outlining the shape of a bottle, starting at the base and going up to a skinny neck. Your weak hand should be open, with palm facing up to form the base. With your dominant hand, start down at the base with an open grip or 'C' hand, then move your hand up an imaginary bottle, closing your grip as you go up.
Bottle is often used in Baby Sign Language to refer to a milk or juice bottle. We prefer using the sign of what is actually in the bottle, for example, signing water, juice, or milk.
We often include the sign for bottle as one of our basic signs. Teach it as soon as your baby shows interest in having their bottle by pointing to the object. Bottle is a great transitional sign to help your baby move from milk, as their nutritional needs change. As your baby becomes more advanced, you can include signs for juice and water.