milk supply for twins

I have 33 week twins in the hospital. The plan is  when they go home is to supplement with neosure because I'm not making enough milk. I make 300 ml right now I am 10 days postpartum but spent 3 days in icu for preeclampsia so it's taking a while to get my supply up. How long did it take to get your supply up and how much do you make? Any pumping schedule/technique that helped you?