Nursing bras

I know they say to not buy nursing bras until after you give birth bc you won't truly know what size to get until then....but rushing to the store after birth doesn't sound appealing to me & im a huge planner. I would like to get 1-2 bras now. Would you get your current size? Or go up a cup size just in case? I was told at breast feeding class if your bra is too tight, it can decrease your milk production. Just curious what others have done. FTM here.