Maternity leave in India is currently three months. Why would you need to join back so early ? Ideally baby needs to feed on mothers milk for the first six months which means that you would surely need to actively express at work. You can store milk for about four hours at room temperature and two days in the fridge longer if deep freezer. It's best not to use a bottle. I would recommend meeting a Lactation specialist to discuss all the options and then choose the one best suited to you.

Please store in the fridge in a clean vessel. You can also store in steel as well.

6 hours in winters.... Otherwise 4 hours..