You can hand express as soon as your baby is born; once you see an increase in the amount of milk expressed, you can use a breast pump.
When Can You Start Using an Electric Breast Pump? - Breasts Friendly
Increasing Breast Milk Supply - Power Pumping – Pregnancy Birth and Beyond
Pumping Breast Milk 101: Breastfeeding & Pumping
3 Ways to Start Pumping While Still Breastfeeding - wikiHow Life
Why And How To Use A Manual Breast Pump
Expressing your breast milk with a pump - Start for Life - NHS
How To Start Breast Pumping
How to Use The Medela Symphony: Quick Start Guide — Breastfeeding Center for Greater Washington
How to use my Spectra Breast Pump: Maximizing settings, suction and cycle levels - LA Lactation, LLC
Pumping: How often, when, and how long to pump breast milk
5 tips to help express breast milk — Feed Eat Speak - Stacey Zimmels
Expressing and storing breast milk
Exclusively Pumping Breast Milk - Breastfeeding Support
Pumping 101: how to use a breast pump - Love and Breast Milk