It is better for him, epescially for breast feeding and brain development. So try to postpone the date at which you will have to rejoin your work. Contemplate all possibilities of leave like extension of maternity leave, earned leave, medical leave, and loss of pay or even temporary break from your job.
If you exhausted all possibilities, then plan to go back to your work, but with lot of precautions. Say no to formula or tinned milk or infant milk substitutes. With little planning one can continue to feed the baby with breast milk. Buy 10 small containers with a capacity of around 100ml with lids. Put all of them in a large vessel and boil and sterilize them and keep it. Whenever the mother is in the home, after feeding extract the remaining milk from the same breast and from the opposite breast and store in the refrigerator at 2- 8 degree celcius. This milk can be kept for 24 hours in the refrigerator at 2- 8 degree celcius. The milk can be kept in the room temperature for 4-6 hours. Always label the container when you collect the milk with date and time. There is no need to reheat the milk and with little planning they can take 1-2 containers ½ an hour before the anticipated feed time and keep it in the room temperature, so that temp will be near the room temperature during the feeding. The baby should be fed only using a spoon or paladai in head up position and bottle should never be used at any cost.
Mother has to pump the breast and remove the milk twice at least during the office hours, otherwise she will get engorged breast which may cause pain and discomfort and also it will lead to reduction of milk secretions. She can collect that milk and store it in the refrigerator in the office and get it back to the home for future use. If no such facility is available, she will have to discard it.
Refer to breast milk expression and storage in guidelines section