I started pumping around 2w. I would pump after her morning feed (about a hour later) for stash most days. If DH was going to give her a bottle, I would pump while he fed her for the missed feed.
I didn't wait, I started pumping right away. I don't know if that's wrong but in my situation it worked out for me. I did a combo of pumping and breastfeeding until my child was 1 year old.
I never tried to build up a big freezer stash, so think I started pumping around 1 oz every other day or so in the morning at around 6 weeks so that I could leave the house sometimes. Then I stopped when I had enough for a couple bottles and I didn't start pumping to build up enough for going back to work until a few weeks before I started. I just pumped an ounce every morning and had plenty on hand for my first day back. If you do it this way, I'd recommend pumping some days before a feeding and some days after a feeding so you get a mix of foremilk and hindmilk.