I am not working yet, but I still pump a ton. Whenever Lily only eats from one side, I pump from the other! Also, once she started sleeping more at night, I would get in an extra pumping session.
The best thing to do is to pump every time your baby would nurse. This will keep up your supply! And when you are at home, on nights and on weekends, be sure to nurse your baby on demand!
You can either get a good freezer stash going and pull from that every day, or you can pump on Monday what you will need for Tuesday, etc, Then Friday's milk can be used for Monday. (Either way, I would try and get a small freezer stash going)
I too was very paranoid about how I was going to get a freezer stash when the baby is nursing all the time! But...10 weeks later, this is what I have! (And I really only started pumping a month ago)