Hand express or pump your milk at work or school. Give your milk to the sitter to feed your baby the next day. Nurse before and after work or school. Have the sitter give your baby formula while you are gone. You may need to express milk during the day for comfort in the early weeks.
Some women find it easy to nurse their baby on one breast, while expressing on the other.
Try to follow the same schedule that you will use when you return to work or school. You can build up a frozen supply of breastmilk this way. Nurse and express in different places, such as the homes of relatives and friends. It will then be easier to nurse at the sitter's and at work or school. When your baby is one month of age, begin offering a supplemental bottle of breastmilk.