How do I know how long to express for?

[Madratlady]

I'm expressing every few hours while ds is in scbu. I'm pumping for about 20 mins each time. Is this enough? There's usually the odd drop drop coming still when I stop but not a lot.

20 mins is about right. You might find this page useful.

Congratulations on your DS.

I would empty both breasts before stopping each time. Sounds like you are doing that already if only the odd drop is coming out. Once your milk gets more established you can switch back to the first breast to see if you get a second let down if you want to express more in volume. Don't keep pumping for ages if the milk isn't coming though as you will just make yourself sore.

Congratulations