I went back to work when DS was 9w and have a desk job with my own office so I can work while pumping. I am able to pump just enough to cover his daily bottles and sometimes get a little bit more for the freezer. The big thing to remember is that you need to drink lots of water, I find some days at work this isn't a problem and others it is time to go and I've barely drank anything because I've been busy.
5:30/6AM-wake DS and nurse
9AM-pump
12PM-pump
3PM-pump
5:30/6PM-get home from work and nurse DS
8PM-pump (sometimes depending upon what else I'm doing
10/10:30-nurse DS