LO is 3 weeks today and that's when my lactation consultant said we could start pumping. I'm completely overwhelmed, to be honest!

When you first started pumping, did you just keep milk on the fridge and then give it to your LO within the same day or couple if days?
Did you immediately start a freezer stash?
How do you know how much expressed milk to give LO?
And how long before you established a comfortable routine?

I'm not going back to work until July/August, so I have time to figure it all out, I'm just not sure where to start.