The phrase "to introduce a bottle" means to give a baby their first experience drinking from a bottle instead of breastfeeding or using a sippy cup. Full definition
We still introduced a bottle of formula when my baby was a few months old, so my husband could help with the feeding and I could get some much - needed rest. (milkandmotherhood.com)
Most experts agree, it's best to introduce a bottle at about 4 weeks of age. (myorganicformula.com)
And not introducing a bottle early can cause stress when you head back to work and your baby refuses a bottle. (rebelliousjezebel.com)