Expressing to return to work

Charlotte 🇬🇧 • Mummy to 2 beautiful little girls. Born 2016 and 2018.

I'm breastfeeding and need to return to work in a couple of months. I'll only be working part time but ideally need at least 1 or 2 bottles to leave for LO. She has a bottle of breast milk before bed and I express at 9.30pm to provide this. She feeds every 2-3 hours.

So I'm wondering when would be best to express a second or third time each day to build up a supply for when I go back to work. Anyone have any advice?