As soon as possible. I pump after every feeding
But to build my milk supply it's recommended to not pump for a certain amount of time after birth.. To just let the baby nurse without any devices for a little while.. How long is that period of time?
About 2 weeks. Feed on demand and get the supply up the start pumping
Also let baby nurse as long as baby wants and try to offer both breasts each time if baby is willing. Pump for about 20 minutes when you pump because you can have more than one let down.