Building a freezer supply

My LO is 10 weeks and i was never able to pump before now because I had oversupply issues. But now my supply is regulated so i really want to start building up a freezer supply. My question is when do i pump (after feedings?)? I also have a haaka should i just use that? And should i do things to up my supply so theres enough for baby and building a stash? Or would that make me have an oversupply again? Im new to this so any tips/recommendations are greatly appreciated!