Breast pump and milk producing question

Soon you guys I will be ordering my breast pump I wanna know which one is the best ? I want one that actually does the job I want to breast feed this time with my twins for a little but my first child I had a spectra s2 and I felt like it didn’t do nothing never seen milk actually come out my nipple (or maybe I wasn’t using it right🤔) and also how long before&after birth can I start pumping ? Do I have to immediately start pumping or I can wait until I get home don’t want my milk to dry up. sorry second time mom and I want to make sure I have enough milk for my twins also will be doing formula too