When should i start pumping and storing milk in preparation for going back to work?

Depends: If you are going back to work at 6 or 8 weeks, you need to store up some milk early. Start pumping and storing by a month. If you have a longer time before you go back, you can wait to store until a month or two before going back. But you will likely be pumping before that in order to give the baby breastmilk in a bottle, an important skill for baby to develop prior to your return to work!

After 2-3 weeks: The first 2-3 weeks after delivery are very hectic. After that, any extra pumped milk can be bagged and stored in a deep freezer for several months. A baggie of milk can be stored in a regular freezer (of a refrigerator) for up to 1 month.