Starting to pump

Jenny • Married mum of 1 <3 🌈

I am six weeks postpartum and I want to start pumping to introduce a bottle at least once at night, and to start building up a freezer supply. I am planning to pump after the first morning feed when my boobs are at their ripest, but I was wondering: do I pump on the same boob he has fed from, or do I do it on the other boob (while he is feeding from the other?) because he only feeds from one boob each feed. Thanks in advance for your help