Yes, expressing about half an hour after a feed is a good way to do it. I never needed to express at night so you shouldn't need to. I found that I would express at any time when I felt a bit full - if DS had gone longer than usual between feeds, or drunk less, and also whenever I had time. I didn't express every day necessarily, but as often as I could. I tried to always have at least a week's worth of EBM in the freezer, and often I had a lot more.

EBM can last for about 4 hours in the fridge after being gently warmed to room temp, as long as the feed hasn't begun. Here are the guidelines for EBM storage and use: Australian Breastfeeding Association -